1.         T. Akazaki, T. Enoki, K. Arai, and Y. Ishii

            "Improving The Characteristics Of An Inalas/Ingaas Inverted Hemt By Inserting An Inas Layer Into The Ingaas Channel"

            Solid-State Electron. 38 (5), 997-1000 (1995).

 

            ABSTRACT: A novel InAlAs/InGaAs inverted HEMT with a thin InAs layer inserted into the InGaAs channel (InAs-inserted-channel i-HEMT) is proposed and its electron transport properties and device performances are investigated. By optimizing the thickness of the InAs layer and its distance from the underlying InAlAs spacer layer, a maximum mobility of 13,600 cm2/Vs at 300 K and 63,500 cm2/Vs at 77 K were attained. The inverted HEMT structure resulted in an extremely high voltage gain, over 60 in a 0.7 mum gate-length device, and a gate-to-drain breakdown voltage as high as 9 V. This voltage gain resulted in a maximum oscillation frequency for a 0.7 mum gate-length device of 81 GHz, 14% higher than that of an InAs-inserted-channel normal HEMT.

 

2.         T. Akazaki, J. Nitta, H. Takayanagi, and K. Arai

            "Superconducting Junctions Using A 2deg In A Strained Inas Quantum-Well Inserted Into An Inalas/Ingaas Md Structure"

            IEEE Trans. Appl. Supercond. 5 (2), 2887-2891 (1995).

 

            ABSTRACT: A newly fabricated three-terminal Josephson junction is coupled with a two-dimensional electron gas (2DEG) in a strained InAs quantum well inserted into an InAlAs/InGaAs modulation-doped structure. The 2DEG is confined in the InAs quantum well and has a maximum mobility of 155,000 cm(2)/Vs at a sheet-carrier density of 1.86 x 10(12) cm(-2) at 10 K. The supercurrent flows through the 2DEG and can be controlled by adjusting the gate voltage. The critical current and normal resistance are measured as a function of the gate voltage, and the sheet-carrier density dependence of the critical current is obtained. We also measure the temperature dependence of the critical current at different gate voltages. The results indicate that, when using this junction, the superconducting characteristics can range between the clean and dirty limits.

 

3.         B. Albinsson, J. W. Downing, L. Goss, H. Schmidbaur, and J. Michl

            "The Conformers Of Oligosilanes"

            Abstr. Pap. Am. Chem. Soc. 209, 316-ORGN (1995).

 

            ABSTRACT:

4.         S. B. Altner, U. P. Wild, and M. Mitsunaga

            "Photon-Echo Demolition Spectroscopy In Eu3+Pr3+Nd3+Y2sio5"

            Chem. Phys. Lett. 237 (5-6), 406-410 (1995).

 

            ABSTRACT: Photon-echo experiments in a Y2SiO5 crystal codoped with Eu3+, Pr3+ and Nd3+ were performed with the objective of studying the influence of excited neighboring ions on the rephasing properties of the ions studied by the coherent transient technique. A strong 'scrambler' pulse was applied to ions of one species before (or while) a two-pulse photon-echo experiment was carried out on a different species. The dependence of the echo intensity on the 'scrambler' wavelength as well as on the time delay between 'scrambler' pulse and echo sequence was investigated. Experimental agreement with a simple model has been obtained.

 

5.         S. Amano, T. Kondo, and K. Kakehi

            "Modality Dependency Of Familiarity Ratings Of Japanese Words"

            Percept. Psychophys. 57 (5), 598-603 (1995).

 

            ABSTRACT: Familiarity ratings for a large number of aurally and visually presented Japanese words were measured for 11 subjects, in order to investigate the modality dependency of familiarity. The correlation coefficient between auditory and visual ratings was.808, which is lower than that observed for English words, suggesting that a substantial portion of the mental lexicon is modality dependent. It was shown that the modality dependency is greater for low-familiarity words than it is for medium- or high-familiarity words. This difference between the low- and the medium- or high-familiarity words has a relationship to orthography. That is, the dependency is larger in words consisting only of kanji, which may have multiple pronunciations and usually represent meaning, than it is in words consisting only of hiragana or katakana, which have a single pronunication and usually do not represent meaning. These results indicate that the idiosyncratic characteristics of Japanese orthography contribute to the modality dependency.

 

6.         H. Ando, A. Chavezpirson, H. Saito, and H. Kanbe

            "Optical-Properties In Fractional-Layer-Superlattice Quantum Wires Calculated By Multiband Effective-Mass Theory"

            J. Appl. Phys. 77 (7), 3372-3377 (1995).

 

            ABSTRACT:

7.         S. Ando, N. Kobayashi, and H. Ando

            "Hexagonal-Facet Laser With Optical Wave-Guides Grown By Selective-Area Metalorganic Chemical-Vapor-Deposition"

            Jpn. J. Appl. Phys. Part 2 - Lett. 34 (1A), L4-L6 (1995).

 

            ABSTRACT: A hexagonal facet (HF) GaAs/AlGaAs laser with rectangular optical waveguides is proposed and its preliminary lasing characteristics are presented. The rectangular waveguide is parallel to one side of the HF laser and consists of the same (111)B growth plane and (110) sidewall facets as the HF laser structure. The number of rectangular waveguides extending from one HF laser is changed from one to four to study the effect of the waveguide on lasing characteristics by optical pumping at room temperature. The lasing light can be efficiently taken out from the point of the rectangular waveguides in all laser structures. These lasers keep a ring cavity mode of inscribed hexagon even if the waveguide structures couple with the HF laser structure.

 

8.         D. G. Austing, T. Honda, Y. Tokura, and S. Tarucha

            "Submicron Vertical Algaas/Gaas Resonant-Tunneling Single-Electron Transistor"

            Jpn. J. Appl. Phys. Part 1 - Regul. Pap. Short Notes Rev. Pap. 34 (2B), 1320-1325 (1995).

 

            ABSTRACT: We explore vertical transport phenomena. in sub-micron asymmetric AlGaAs/GaAs double barrier structures (DBS's) by applying a bias to a special Schottky side gate which allows the effective area of the conducting channel to be adjusted or ''tuned''. The AlGaAs barriers are selectively doped to generate Excess electrons in the GaAs well, and thus single electron transistor (SET) operation is possible because the number of electrons in the quantum dot can be varied one-by-one with the side gate. Gate modulation of the drain current flawing through the conducting channel is found to be strong, and this allows us to study Coulomb blockade, electron-electron interactions and lateral confinement effects. Observation of a broad (approximate to 18 mV) current plateau at low bias when the quantum dot is occupied by a single electron, suggests that this technology is very promising for the realization of SET operation at temperatures well above 4.2 K.

 

9.         B. C. Barnett, L. Rahman, M. N. Islam, Y. C. Chen, P. Bhattacharya, W. Riha, K. V. Reddy, A. T. Howe, K. A. Stair, H. Iwamura, S. R. Friberg, and T. Mukai

            "High-Power Erbium-Doped Fiber Laser Mode-Locked By A Semiconductor Saturable Absorber"

            Opt. Lett. 20 (5), 471-473 (1995).

 

            ABSTRACT: Using an erbium-doped fiber laser (EDFL) passively mode lacked by a semiconductor saturable absorber, we generate 5.5-ps pulses of a 2.3-nJ/pulse, which are more than three times higher in energy than for other reported EDFL's. We show that, by introduction of a Linear loss element within the cavity, multiple pulsing behavior at high pump powers can be suppressed. We also determine the saturable-absorber characteristics-absorbance versus wavelength near band gap-that are necessary to produce short mode-locked pulses.

 

10.       H. Cao, J. Jacobson, G. Bjork, S. Pau, and Y. Yamamoto

            "Observation Of Dressed-Exciton Oscillating Emission Over A Wide Wavelength Range In A Semiconductor Microcavity"

            Appl. Phys. Lett. 66 (9), 1107-1109 (1995).

 

            ABSTRACT:

11.       H. Cao, G. Klimovitch, G. Bjork, and Y. Yamamoto

            "Theory Of Direct Creation Of Quantum-Well Excitons By Hole-Assisted Electron Resonant-Tunneling"

            Phys. Rev. B 52 (16), 12184-12190 (1995).

 

            ABSTRACT: We have investigated a resonant tunneling process: the direct creation of GaAs quantum well excitons through hole-assisted electron resonant tunneling. The current density of this tunneling process is on the same order of magnitude as the usual electron resonant tunneling current density. However, the two-particle nature of such a tunneling process makes it different from the conventional one-particle (electron, hole, or exciton) tunneling process, and in fact it is another type of assisted tunneling as compared with the phonon-assisted tunneling. This tunneling process may open a door toward electrically pumped excitonic cavity quantum electrodynamics and optoelectronic devices.

 

12.       H. Cao, G. Klimovitch, G. Bjork, and Y. Yamamoto

            "Direct Creation Of Quantum-Well Excitons By Electron Resonant-Tunneling"

            Phys. Rev. Lett. 75 (6), 1146-1149 (1995).

 

            ABSTRACT: We have demonstrated a new tunneling process: the direct creation of GaAs quantum well excitons through electron resonant tunneling. The two-particle nature of such a tunneling process makes it different from the ordinary one-particle (electron, hole, or exciton) tunneling process in resonant tunneling conditions and results in different I-V characteristics. This resonant tunneling process may open a door toward electrically pumped excitonic cavity quantum electrodynamics and optoelectronic devices.

 

13.      E. P. F. Chan and R. vanderMeyden

            "Testing containment of object-oriented conjunctive queries is Pi(p)(2)-hard"

            in Computing And Combinatorics, Lecture Notes In Computer Science Vol. 959 (Springer-Verlag Berlin, Berlin 33, 1995), pp. 81-90.

 

            ABSTRACT: We study the complexity of testing containment for a class of object-oriented conjunctive queries. We show that the containment problem is Pi(2)(p)-hard. Together with a previous result, the containment problem is complete in Pi(2)(p).

 

14.       A. Chavezpirson, O. Vatel, M. Tanimoto, H. Ando, H. Iwamura, and H. Kanbe

            "Nanometer-Scale Imaging Of Potential Profiles In Optically-Excited N-I-P-I Heterostructure Using Kelvin Probe Force Microscopy"

            Appl. Phys. Lett. 67 (21), 3069-3071 (1995).

 

            ABSTRACT: We report on measurements of the potential profile of a GaAs/AlCaAs n-i-p-i multiple quantum well structure using a scanning Kelvin probe force microscope (KFM). Using this novel technique we directly measure with meV precision and sub-100 nm spatial resolution the potential difference between n-i-p-i layers with and without external optical excitation, The measured potential profiles, which have not been directly imaged previously, agree well with potential profiles calculated for optically excited n-i-p-i structures, but modified by band bending effects at the surface. (C) 1995 American Institute of Physics.

 

15.       M. J. Ekenstedt, H. Yamaguchi, and Y. Horikoshi

            "Indium desorption from InAs surfaces and its dependence on As coverage"

            Appl. Phys. Lett. 67 (26), 3948-3950 (1995).

 

            ABSTRACT: The desorption rate of In atoms from an InAs surface and its dependence on surface As coverage is reported. InAs films were grown by molecular beam epitaxy on fully strained 1 monolayer thick In0.75Ga0.25As films deposited on (001) InAs substrates. Using a sensitive technique based on reflection high-energy electron diffraction, the desorption rate for In is found to be highly dependent on the As coverage. During a sublimation process, where In from an InAs surface is desorbed, the desorption rate at 510 degrees C is five times greater for a group III stabilized surface than for an As-stabilized surface. The difference in desorption rate is believed to be related to changes in the In to surface bond strengths. (C) 1995 American Institute of Physics.

 

16.       M. J. Ekenstedt, H. Yamaguchi, and Y. Horikoshi

            "Reconstruction Dependent Indium Segregation"

            Jpn. J. Appl. Phys. Part 2 - Lett. 34 (2A), L163-L166 (1995).

 

            ABSTRACT: Fully strained In0.5Ga0.5 As layers are grown on InAs substrates in order to measure the degree of In segregation, and its dependence on surface reconstruction and substrate temperature by reflection high energy electron diffraction. We find that segregation is reduced for an As-covered 2 x 4 reconstructed surface as compared to a group III stabilized surface. Results show that the segregation process occurs primarily between the surface and the first subsurface layer. We present evidence showing that the effect a 1 Ml In0.5Ga0.5 As layer deposited on InAs has on the As-desorption is countered for by capping the layer with 6 to 10 monolayers of InAs.

 

17.       M. J. Ekenstedt, H. Yamaguchi, and Y. Horikoshi

            "Effects Of Alloy Composition On The As Desorption From And Adsorption On Strained Inxga1-Xas Surfaces"

            J. Cryst. Growth 150 (1-4), 473-477 (1995).

 

            ABSTRACT: The specular reflectivity of strained InxGa1-xAs surfaces grown by molecular beam epitaxy on InAs (100) substrates is measured with reflection high-energy electron diffraction (RHEED). A discontinuous change in the surface reflectivity is observed as the substrate temperature is increased above the transition point where As desorbs from the surface. A clear hysteresis loop is revealed as the substrate temperature is decreased. The substrate temperature required for desorption of surface As increases with Ga composition. A comparison between experimental results and theoretical calculations based on a Monte Carlo simulation shows that the average vertical interaction is increasing with Ga fraction. Fluctuations in alloy composition across the surface result in In-rich domains from which As is preferentially desorbed. The sudden loss of As, corresponding to a first order phase transition, occurs when the As desorbed domains attain a critical size. The metastability of the phase transition is shown to be a minimum for In0.5Ga0.5As layers.

 

18.       S. R. Friberg and R. J. Hawkins

            "Compton-Scattering Of Electrons From Optical Pulses For Quantum-Nondemolition Measurements"

            J. Opt. Soc. Am. B-Opt. Phys. 12 (1), 166-169 (1995).

 

            ABSTRACT: Compton scattering of electrons from photons destroys neither electrons nor photons, permitting quantum nondemoliton measurements of the photon number. Here we consider a Compton scattering quantum nondemolition measurement of the photon number of an optical pulse traveling in a prepared optical fiber. A beam of electrons is directed through the evanescent field associated with the optical pulse, causing the electrons to scatter through an angle proportional to the pulse's photon number.

 

19.       M. Fujino, T. Hisaki, and N. Matsumoto

            "Preparation And Characterization Of Fluoropropyl-Substituted Polysilane Copolymers - Poly(3,3,3-Trifluoropropylmethylsilane-Co-Methylpropylsilane)"

            J. Polym. Sci. Pol. Chem. 33 (13), 2279-2283 (1995).

 

            ABSTRACT:

20.       M. Fujino, T. Hisaki, and N. Matsumoto

            "Electrochromism In An Organopolysilane"

            Macromolecules 28 (14), 5017-5021 (1995).

 

            ABSTRACT: This paper reports solid-state electrochromism observed in poly[(3,3,3-trifluoropropyl)-methylsilane-co-methylpropylsilane]. The UV absorption increases by ca. 50% at 3.1 x 10(8) V m(-1) accompanied by a 5-nm red shift of the lambda(max). The response time is less than 100 ms. The absorption recovers when the electric field is removed. This electrochromic behavior is rationalized in terms of structural changes in the silicon chain, which is the first known example of electrochromism not involving an electrochemical reaction.

 

21.       Y. K. Fukai, H. Nakano, S. Nakata, S. Tarucha, and K. Arai

            "Transition From Weak To Strong Spin-Orbit Scattering Regime In Diffusive Ingaas/Inalas Quantum Wires"

            Solid State Commun. 94 (9), 757-761 (1995).

 

            ABSTRACT: Spin-orbit interaction in InGaAs/InAlAs quantum wires is investigated by measuring conductance fluctuations at temperatures ranging from 2 K down to 0.06 K. The resistance of an InGaAs/InAlAs wire in a zero magnetic field decreases as the temperature decreases below 1.6 K. This temperature dependence is reproduced by the theory of antilocalization in the strong spin-orbit interaction regime. In the same temperature range, the conductance fluctuation amplitude increases nonmonotonically with decreasing temperature. This behavior is attributed to the temperature-induced transition from the weak to the strong spin-orbit scattering regime in the mesoscopic disordered system.

 

22.       K. Furukawa, M. Fujino, and N. Matsumoto

            "Crystal-Structure And Optical-Properties Of Polymorphic Octasilacubane - Comment"

            Appl. Phys. Lett. 66 (10), 1291-1291 (1995).

 

            ABSTRACT:

23.       S. Goto and H. Nojima

            "Equilibrium-Analysis Of The Distribution Of Information In Human-Society"

            Artif. Intell. 75 (1), 115-130 (1995).

 

            ABSTRACT: This paper applies equilibrium analysis in micro-economics to analyze a stable structure in a model of human society. The structure is observed in the study of the distribution of information. It forms a three-layered hierarchy. These layers are called brains, gatekeepers and end users. The three-layer structure is widely observed in a variety of research fields. For example, in computer networks, core gateways correspond to brains, stub gateways behave like gatekeepers, and local networks are end users. The three-layer model is considered to be an essential extension of the popular ''client-server'' concept in computer science. This paper calculates the supply and demand curves in micro-economics to show how the equilibrium is established. The law of diminishing utility is utilized to represent the distribution of information or knowledge. The calculations are straightforward if the dependence of the end users on the other layers is taken into account. The results can explain many properties of the three-layer model.

 

24.       Y. Harada, H. Takayanagi, and A. A. Odintsov

            "Coherent Cooper-Pair Tunneling In A Superconducting Single-Electron Transistor"

            Jpn. J. Appl. Phys. Part 1 - Regul. Pap. Short Notes Rev. Pap. 34 (8B), 4572-4574 (1995).

 

            ABSTRACT: We investigate how coherent Cooper-pair tunneling depends on the competition between Josephson coupling energy E(J) and charging energy E(C). Measurements were performed on a circuit consisting of two dc-SQUIDs in series, with a gate capacitively coupled to the central island. As the E(J)/E(C) ratio decreased, coherent Cooper pairs tended to tunnel incoherently. Measured data show good agreement with theoretical calculations in strong and weak coupling limits. This experiment implies the manifestation of Heisenberg's uncertainty principle in a superconductor.

 

25.       I. Hashimoto, T. Mashiko, T. Mizuta, T. Imada, Y. Iwase, H. Okazaki, and K. Yoshikawa

            "Multichannel Detection Of Magnetic Compound Action Fields With Stimulation Of The Index And Little Fingers"

            Electromyogr. Mot. Control-Electroencephalogr. Clin. Neurophysiol. 97 (2), 102-113 (1995).

 

            ABSTRACT: Magnetic compound action fields (CAFs) over the right arm were measured from 63 sensor positions with two 7-channel SQUID gradiometer systems following electrical stimulation of the index and little fingers as well as the ring finger separately. The wave forms of the CAFs were primarily biphasic, corresponding to the depolarization and repolarization currents of the stimulated nerves. Maximum amplitudes of the CAFs were 60-140 fT for the index finger stimulation and 40-90 fT for the little finger stimulation. The field mapping of the CAFs revealed a propagating quadrupolar pattern with different distributions for the index and little fingers. The results agree with the anatomical location of the median and ulnar nerves for the index and little finger stimulation respectively. The isofield maps, due to ring finger stimulation, showed complex patterns as a result of simultaneous activation of the median and ulnar nerves. By comparing the amplitudes of the maxima of the CAFs due to index finger stimulation with those after median nerve stimulation at the wrist, the numerical ratios of the constituent digital nerve fibers for the index finger within the median nerve at the wrist were estimated. The ratios of 0.14-0.41 (mean 0.27), determined with measurement of the CAFs, are fairly consistent with those calculated from the reported histological data.

 

26.       I. Hashimoto, T. Mashiko, K. Yoshikawa, T. Mizuta, T. Imada, and M. Hayashi

            "Neuromagnetic Measurements Of The Human Primary Auditory Response"

            Evoked Potential.-Electroencephalogr. Clin. Neurophysiol. 96 (4), 348-356 (1995).

 

            ABSTRACT: The spatio-temporal organization of the human primary auditory response (N19 and P30) was determined by analyzing magnetic fields from the right hemisphere evoked by monaural clicks to the left ear. The magnetic response consisted of peaks corresponding to electrical N19 (N19m) and P30 (P30m) within 40 msec after stimulation. However, the onset of electrical N19 occurred 5-9 msec earlier than that of the magnetic counterpart. Furthermore, the relative amplitude of N19 and P30 (N19/P30) was larger (more than 1) than that (about 0.5) of N19m and P30m (N19m/P30m). The findings suggest an additional contribution from a subcortical source for electrical N19. The estimated equivalent sources for N19m and P30m were localized at the postero-medial part of Heschl's gyrus (the primary auditory cortex). Furthermore, the dipole orientation of N19m was directed postero-ventrally and that of P30m was in the opposite direction, which is compatibile with the anatomy of the supratemporal primary auditory cortex. These results resolve a long standing controversy of cortical vs. subcortical structures as the generators of the N19.

 

27.       N. Hatakenaka, T. Ogawa, and S. Kurihara

            "Generation Of Squeezed Photons By Coupled Phase-Conjugate Resonators"

            Phys. Lett. A 204 (3-4), 223-228 (1995).

 

            ABSTRACT: We study the generation of squeezed photons by coupled resonators with phase-conjugate mirrors. A large amount of squeezing is obtained by an interference effect between them even when optical nonlinearities are small. Squeezing can be controlled by the phase difference of the laser beams pumping the phase-conjugate mirrors. This is analogous to the Josephson supercurrent.

 

28.       H. Hibino, Y. Homma, and T. Ogino

            "Real-Space Observation Of (111) Facet Formation On Vicinal Si(111) Surfaces"

            Phys. Rev. B 51 (12), 7753-7761 (1995).

 

            ABSTRACT:

29.       H. Hibino and T. Ogino

            "Reducing Domain Boundaries Of Surface Reconstruction During Molecular-Beam Epitaxy On Si(111)"

            Appl. Phys. Lett. 67 (7), 915-917 (1995).

 

            ABSTRACT: We report the behavior of steps and out-of-phase boundaries (OPBs) of 7X7 reconstruction on Si(lll) during Si molecular beam epitaxy. During step-flow growth, Si atoms are preferentially incorporated into the crystal at positions where steps are connected with OPBs on the lower terraces, resulting in sawtooth shaped steps. This heterogeneous advancement of steps causes OPBs to rearrange and thereby reduce in number. (C) 1995 American Institute of Physics.

 

30.       H. Hibino and T. Ogino

            "Exchanges Between Si And Pb Adatoms On Si(111)"

            Surf. Sci. 328 (3), L547-L552 (1995).

 

            ABSTRACT: Real-time observation by high-temperature scanning tunneling microscopy of exchanges between Si and Pb atoms on a Si(111)-root 3 X root 3 surface is reported. The exchange rate is obtained as a function of the temperature. The activation energy of the exchange is about 1.2 eV, and the prefactor, shown to depend on the Pb coverage, is from 2 X 10(10) to 8 X 10(11) s(-1). This prefactor is much larger than that for the exchange between Pb and Ge adatoms on a Ge(111)-c(2 X 8) surface, indicating that the adatom arrangement greatly influences the exchange mechanism. We also report that metastable 9 x 9 reconstruction appears during Pb desorption.

 

31.       S. Hirono, M. Igarashi, Y. Koshimoto, and Y. Maeda

            "Compositionally Separated Microstructure Of Co-Cr Films Prepared By Electron-Cyclotron-Resonance Plasma Sputtering"

            IEEE Trans. Magn. 31 (6), 2812-2814 (1995).

 

            ABSTRACT: Compositional separation (CS) has been observed to occur in Co-Cr-based alloy thin films grown at elevated substrate temperatures. This GS produces fine Co-enriched regions within grains, which are expected to give a magnetic microstructure suitable for high-density recording. We studied the compositional microstructure in Co-Cr films grown by electron-cyclotron-resonance plasma (ECR) sputtering with a view to reducing media noise and increasing recording density. ECR sputtering produced fine grains which supported particularly small and closely packed Co-enriched regions (less than 5 nm spacing) at elevated substrate temperature. This compositional microstructure is finer than that of RF-sputtered Co-Cr films. ECR sputtering simultaneously improves the magnetic properties and refines the compositional microstructure.

 

32.       Y. Hirota and T. Fukuda

            "Scanning-Tunneling-Microscopy Study Of Gaas(001) Surface Prepared By Deoxygenated And Deionized Water-Treatment"

            Appl. Phys. Lett. 66 (21), 2837-2839 (1995).

 

            ABSTRACT:

33.       Y. Hirota, T. Ogino, Y. Watanabe, and M. Oshima

            "Thermal Effects On Gaas(001) Surface Prepared By Deoxygenated And Deionized Water-Treatment"

            J. Vac. Sci. Technol. A-Vac. Surf. Films 13 (3), 1676-1680 (1995).

 

            ABSTRACT:

34.       Y. Homma, H. Hibino, and N. Aizawa

            "Direct Evidence For Ge Preferential Growth At Steps And Out-Of-Phase Boundaries Of (7x7) Domains On Si(111) In Solid-Phase Epitaxy"

            Surf. Sci. 324 (1), L333-L336 (1995).

 

            ABSTRACT: Ge solid phase epitaxy on a Si(111) surface has been directly observed by secondary electron surface microscopy which is based on scanning electron microscopy. Ge island formation initially occurs at steps and out-of-phase boundaries of (7 x 7) domains. These results confirm the origin of previously reported mesh patterns of Ge islands grown on Si(111).

 

35.       T. Honda, S. Tarucha, T. Saku, and Y. Tokura

            "Quantized Conductance Observed In Quantum Wires 2-Mu-M To 10-Mu-M Long"

            Jpn. J. Appl. Phys. Part 2 - Lett. 34 (1A), L72-L75 (1995).

 

            ABSTRACT: We observe quantized conductance in 2- to 10-mum-long wires formed in a very-high-mobility modulation-doped heterostructure. These wires have a new gate configuration that facilitates strong lateral constriction despite the large separation between the surface and the electron channel. Random potential scattering in the wire causes a conductance dip near the threshold of the higher-lying subband. This scattering is strongly suppressed when only the ground subband is occupied. Wires longer than 20 mum display a conductance step of 0.6 to 0.7 (2e2/h). This step is probably made more evident by the effect of thermal broadening as well as by a dip in the conductance near the threshold for the higher-lying subband.

 

36.       K. Hono, K. Yeh, Y. Maeda, and T. Sakurai

            "3-Dimensional Atom-Probe Analysis Of A Sputter-Deposited Co-Cr Thin-Film"

            Appl. Phys. Lett. 66 (13), 1686-1688 (1995).

 

            ABSTRACT:

37.       T. Horiuchi, O. Niwa, and M. Morita

            "Fabrication And Photoelectrochemical Properties Of Interdigitated Array Microelectrodes Consisting Of Optically Transparent And Nontransparent Band Electrodes"

            J. Electrochem. Soc. 142 (9), L146-L149 (1995).

 

            ABSTRACT: A lithographic fabrication method for a new interdigitated array microelectrode (IDA) consisting of optically transparent (ITO) and nontransparent (Pt) arrays of band electrodes on a quartz substrate is presented. The new IDA is applied to the Ru(bpy)(3)(2+)-Fe3+ photogalvanic system. The effective separation of photoinduced active species between Very closely spaced electrodes is achieved by utilizing the shadow of the nontransparent electrode generated by illumination from the rear of the IDA. This back-illumination method using the new IDA is effective in increasing the conversion efficiency.

 

38.       B. Huttner, N. Imoto, N. Gisin, and T. Mor

            "Quantum Cryptography With Coherent States"

            Phys. Rev. A 51 (3), 1863-1869 (1995).

 

            ABSTRACT:

39.       K. Igeta and T. Ogawa

            "Information Dissipation In Quantum-Chaotic Systems - Computational View And Measurement Induction"

            Chaos Solitons Fractals 5 (7), 1365-1379 (1995).

 

            ABSTRACT: Information dissipation, a key concept in solving problems in physics of complex systems (e.g. defining physical reversibility and classical-quantum correspondence), is investigated from viewpoints of computation and measurement. First, a fundamental relationship between energy dissipation and the time required for information erasure is derived in the context of computation processes. Next, we review the nonunitarity and irreversibility in quantum-mechanical measurement processes, discussing the possibility of generating the Schrodinger-cat state (the quantum-mechanical superposition of macroscopically distinguishable states). In a quantum-chaotic system, in particular, suppressed chaotic behaviours can revive by the nonunitary measurements. There, nonunitary information dissipation from the relevant system to an external system (a measurement apparatus) plays essential roles.

 

40.       T. Imielinski, R. vanderMeyden, and K. V. Vadaparty

            "Complexity tailored design: A new design methodology for databases with incomplete information"

            J. Comput. Syst. Sci. 51 (3), 405-432 (1995).

 

            ABSTRACT: This paper introduces a new design methodology, complexity tailored degn, for databases containing incomplete information. The novelty of the approach is that it introduces query complexity as a consideration in database design. In general, the problem of evaluating queries in databases with incomplete information is intractable. Complexity tailored design consists in setting the values of database design parameters so as to guarantee the efficient (polynomial time) evaluability of selected queries. We develop this approach for OR-databases, which are obtained by extending relational databases with OR-objects that express restricted disjunctions; OR-objects occur naturally in planning. scheduling and design applications. We consider two design parameters: (i) typing that delimits the columns in which OR-objects may occur, and (ii) degree of co-reference that determines how OR-objects may be repeated within the database. We establish, for a broad class of queries in OR-databases, a complete syntactic characterization that classifies the data complexity of each query as being either in PTIME or co-NP complete, given a setting of the database design parameters. This characterization can then be used in complexity tailored design to determine ''maximal'' schemata for which the queries of interest to the user are evaluable in PTIME. (C) 1995 Academic Press, Inc.

 

41.       H. Isaka, H. Teramae, M. Fujiki, and N. Matsumoto

            "Sigma-Conjugation In A Periodic Polycarbosilane, Poly[1,1,2,2-Tetramethyldisilylenemethylene]"

            Macromolecules 28 (13), 4733-4735 (1995).

 

            ABSTRACT:

42.       H. Ishii, A. Yuyama, S. Narioka, K. Seki, S. Hasegawa, M. Fujino, H. Isaka, M. Fujiki, and N. Matsumoto

            "Photoelectron-Spectroscopy Of Polysilanes, Polygermanes And Related-Compounds"

            Synth. Met. 69 (1-3), 595-596 (1995).

 

            ABSTRACT: Ultraviolet photoelectron spectra were measured for five polysilanes, two polygermanes, three Si-Ge copolymers and tert-butyloctasilacubane. The UPS spectra of the polyalkrylsilanes and polyalkylgermanes indicate that the valence electronic structure can be regarded as an overlap of those of the backbone and substituents. On the other hand, the spectra of polyarylsilanes imply that the uppermost part of the valence band structure is slightly different from the superposition of those of the Si backbone and substituents due to sigma-pi interaction. The results of copolymers and tert-butyloctasilacubane are also discussed.

 

43.       J. Jacobson, S. Pau, H. Cao, G. Bjork, and Y. Yamamoto

            "Observation Of Exciton-Polariton Oscillating Emission In A Single-Quantum-Well Semiconductor Microcavity"

            Phys. Rev. A 51 (3), 2542-2544 (1995).

 

            ABSTRACT:

44.       M. Kasu and N. Kobayashi

            "Surface-Diffusion Of Alas On Gaas In Metalorganic Vapor-Phase Epitaxy Studied By High-Vacuum Scanning-Tunneling-Microscopy"

            Appl. Phys. Lett. 67 (19), 2842-2844 (1995).

 

            ABSTRACT: After depositing a 1/6 monolayer of AlAs on a very flat GaAs (001) surface by metalorganic vapor-phase epitaxy, we have studied AlAs two-dimensional (2D) nuclei by high-vacuum scanning tunneling microscopy. AlAs 2D nuclei elongate in the [110] direction, like GaAs. The density of AlAs 2D nuclei in the saturation region was 5x10(10) cm(-2) at 580 degrees C. The saturated AlAs 2D nucleus density decreased as the temperature increased. From the saturated AlAs 2D nucleus densities the surface diffusion coefficient of AlAs on GaAs was calculated to be 1.5 X 10(-7) cm(2)/s at 530 degrees C. This is one order of magnitude smaller than that of GaAs on GaAs. (C) 1995 American Institute of Physics.

 

45.       M. Kasu and N. Kobayashi

            "Surface-Diffusion And Step-Bunching Mechanisms Of Metalorganic Vapor-Phase Epitaxy Studied By High-Vacuum Scanning-Tunneling-Microscopy"

            J. Appl. Phys. 78 (5), 3026-3035 (1995).

 

            ABSTRACT: On a very flat GaAs surface we grow a 1/6 monolayer amount of GaAs by metalorganic vapor-phase epitaxy and observe two-dimensional (2D) nuclei by high-vacuum scanning tunneling microscopy. From the 2D nucleus densities we calculate the surface diffusion coefficient of 2x10(-6) cm(2)/s at 530 degrees C. During growth, the bunched step (multistep) separation saturates and is independent of the substrate misorientation angle. These results can be explained by a mechanism that takes into account both 2D nuclei formation on a wider terrace and their coalescence on ascending steps. A step-bunching simulation based on our model reveals that the saturated multistep separation is proportional to the 2D nucleus separation, i.e., the inverse of the square root of the density. (C) 1995 American Institute of Physics.

 

46.       T. Kawabata

            "Topic-focusing mechanism for speech recognition based on probabilistic grammar and topic-Markov model"

            Syst. Comput. Jpn. 26 (13), 75-82 (1995).

 

            ABSTRACT: Speech conversion can be considered as the most comfortable means of information transmission between the human and the machine. To realize such a mechanism, there must be a technique for efficient natural language processing. This paper proposes a new topic-control mechanism based on the statistical technique as a means to ameliorate the complexity of the natural language processing. The input speech is analyzed using the predictive CFG. The sequence of generated grammatical rules in used to drive HMM, and the topic is identified as the bias of the state distribution. Conversely, the bias of the distribution is reflected dynamically on the probabilities of the grammatical rules, thus, recognition search space is narrowed. Using the large-scale dialogue database, the reduction effect for the perplexity to the text data input is evaluated, and it is verified that the proposed method has a high power to narrow the search space.

 

47.       M. Kawashima, T. Saku, and Y. Horikoshi

            "Characteristics Of Algaas/Gaas Heterostructures Grown By Migration-Enhanced Epitaxy At High-Temperatures"

            Semicond. Sci. Technol. 10 (9), 1237-1246 (1995).

 

            ABSTRACT: Migration-enhanced epitaxy at relatively high temperatures has been reported to deteriorate the crystal quality and photoluminescence characteristics of AlGaAs/GaAs heterostructures, and we investigated this phenomenon by comparing the AlGaAs/GaAs heterostructures grown by migration-enhanced epitaxy with those grown by conventional molecular beam epitaxy. The single-quantum-well structures grown by migration-enhanced epitaxy at 580 and 660 degrees C exhibited defect-induced photoluminescence. Consideration of the surface equilibrium suggests that this degradation is caused by the evaporation of As from the growing surface, and we found that this can be prevented by applying a supplementary As beam during the deposition of Ga or Al or both. This supplementary beam is much less intense than that needed to sustain the growth by molecular beam epitaxy (only 5% at 580 degrees C). The photoluminescence degradation reported by others, however, is too extensive to be reproduced in our experiment even considering the shortage of As on the growing surface. Their result may be caused by an additional contamination-net directly related to the migration-enhanced epitaxy process.

 

48.       J. S. Kim, H. F. Kan, and Y. Yamamoto

            "Macroscopic Coulomb-Blockade Effect In A Constant-Current-Driven Light-Emitting Diode"

            Phys. Rev. B 52 (3), 2008-2012 (1995).

 

            ABSTRACT: The intensity squeezing bandwidth of a light-emitting diode was measured as functions of a driving current, junction capacitance, and operation temperature. It was found that the squeezing bandwidth was linearly proportional to the current and inversely proportional to the capacitance and the temperature in a low current regime. The experimental results provide evidence for a pump-noise-suppression mechanism in a constant-current-driven p-n junction due to a ''macroscopic Coulomb blockade effect'' [A. Imamoglu and Y. Yamamoto, Phys. Rev. Lett. 70, 3327 (1993)].

 

49.       M. S. Kim and N. Imoto

            "Phase-Sensitive Reservoir Modeled By Beam-Splitters"

            Phys. Rev. A 52 (3), 2401-2410 (1995).

 

            ABSTRACT: The superposition of input fields in a lossless beam splitter is studied in the Schrodinger picture by using the convolution of the positive P representations, and the convolution law for these representations is extended to other quasiprobability functions such as the Wigner and Q functions. We show that the reservoir can be modeled by an infinite array of beam splitters, and we use the convolution law and this model to derive the Fokker-Planck equation for a system coupled with a phase-sensitive reservoir. Solving this equation shows that a phase-sensitive attenuation and amplification can be described by the superposition of two independent quantum fields, one of which is the initial signal field and the other the squeezed thermal noise field representing the reservoir.

 

50.       T. Kimura

            "Basic And Applied-Research At Ntt And Postgraduate Education"

           Aust. J. Phys. 48 (2), 233-257 (1995).

 

            ABSTRACT: Several current research topics, which are studied at NTT Basic Research Laboratories, are reviewed in the fields of semiconductor physics, quantum optics and biophysics. These topics include the surface structure transition of GaAs, InAs and Si, electron transport in low dimensional structure, microcavity quantum-wire semiconductor lasers, quantum nondemolition measurement of fibre solitons, and artificial network development of cultivated neural cells.

 

51.       K. Kinoshita and T. Yamada

            "Pb1-Xsnxte Crystal-Growth In-Space"

            J. Cryst. Growth 147 (1-2), 91-98 (1995).

 

            ABSTRACT: Pb1-xSnxTe crystals were grown by the directional solidification method under microgravity in the SL-J/FMPT mission on board the space shuttle ''Endeavor''. A cylindrical crystal, 15 mm in diameter and 58 mm in length, was obtained. A constant SnTe mole fraction of about 0.16 (i.e., a constant Pb/Sn ratio) was achieved along the growth axis to a distance of about 10 mm, and the etch pit density was about one-tenth that of a terrestrially grown crystal. The space-grown crystal had also improved electrical properties. In addition, about 25 spherical crystals, ranging from 0.5 to 11 mm in diameter, were unintentionally formed on the graphite spring.

 

52.       Y. Kobayashi, K. Prabhakaran, and T. Ogino

            "Thermal Clustering Of Very Thin Oxide Formed On Si Surfaces By N2o/O-2 Adsorption"

            Surf. Sci. 329 (3), 167-176 (1995).

 

            ABSTRACT: Thermal clustering of ultrathin oxide layers with 1 monolayer thickness on Si(111) and Si(001) surfaces was studied using Auger electron spectroscopy (AES) and ultraviolet photoelectron spectroscopy (UPS). Uniform oxide layer formed by self-limited adsorption of N2O or O-2 at room temperature is deformed inhomogeneously to form oxide clusters by annealing at about 400 degrees C, which is a much lower temperature than oxide decomposition temperature (about 650 degrees C). AES analysis showed that the area of the bare Si surface exposed as a result of this clustering is 10%-15% of the original surface. Exposure of the clean surface was confirmed by the reappearance of surface state in UPS after annealing. Consideration of surface energy reported in the literature suggests that the driving force of the clustering phenomenon is mainly due to an increase of the Si-O-Si bond angle on annealing.

 

53.       Y. Kobayashi, K. Uwai, and N. Kobayashi

            "Chemical-Structure Of As-Stabilized Surface During Gaas Metalorganic Vapor-Phase Epitaxy Studied By Surface Photoabsorption"

            Jpn. J. Appl. Phys. Part 1 - Regul. Pap. Short Notes Rev. Pap. 34 (6A), 3008-3011 (1995).

 

            ABSTRACT: As-stabilized surface structures during GaAs metalorganic vapor phase epitaxy (MOVPE) are investigated by taking a difference in surface photo-absorption spectrum between two principal axes, which produces the surface anisotropic spectra mainly due to As dimers on the surface. We established the surface phase diagram as a function of substrate temperature and AsH3 partial pressure. Below 630 degrees C, independently of AsH3 partial pressure, the surface is c(4 x 4)-like whose As dimers have a bond axis parallel to [110]. As the substrate temperature increases and the AsH3 partial pressure decreases, the surface evolves to (2 x 4)gamma-like which contains As dimers having a bond axis parallel to [$($) over bar$$ 110]. At a substrate temperature of around 600 degrees C, a phase diagram comparison between MOVPE and molecular beam epitaxy (MBE) shows that the c(4 x 4)-like surface is stable in MOVPE, while the (2 x 4) surface is stable in MBE. The characterization of step structure by atomic force microscopy shows that the difference of As structures has a significant effect on the step straightening mechanism.

 

54.       R. C. Liu and Y. Yamamoto

            "Conductance Dependent Suppression Of Current Partition Noise In Mesoscopic Electron Branching Circuits"

            Physica B 210 (1), 37-42 (1995).

 

            ABSTRACT: Inelastic scattering subject to local charge conservation realizes the transition from ballistic to dissipative electron division, and suppresses the current partition noise in mesoscopic electron branching circuits. The relevant parameter for noise suppression is the output conductance and not the location of the scatterers. We find the noise in an electron beam splitter (Y-branch) decreases linearly (nonlinearly) with decreasing conductance. Physically, the suppression mechanism is a natural implementation of the measurement and feedback control of electron numbers.

 

55.       E. Maeda, H. P. C. Robinson, and A. Kawana

            "The Mechanisms Of Generation And Propagation Of Synchronized Bursting In Developing Networks Of Cortical-Neurons"

            J. Neurosci. 15 (10), 6834-6845 (1995).

 

            ABSTRACT: The characteristics and mechanisms of synchronized firing in developing networks of cultured cortical neurons were studied using multisite recording through planar electrode arrays (PEAs). With maturation of the network (from 3 to 40 d after plating), the frequency and propagation velocity of bursts increased markedly (approximately from 0.01 to 0.5 Hz and from 5 to 100 mm/sec, respectively), and the sensitivity to extracellular magnesium concentration (0-10 mM) decreased. The source of spontaneous bursts, estimated from the relative delay of onset of activity between electrodes, varied randomly with each burst. Physical separation of synchronously bursting networks into several parts using an ultraviolet laser, divided synchronous bursting into different frequencies and phases in each part. Focal stimulation through the PEA was effective at multiple sites in eliciting bursts, which propagated over the network from the site of stimulation. Stimulated bursts exhibited both an absolute refractory period and a relative refractory period, in which partially propagating bursts could be elicited. Periodic electrical stimulation (at 1 to 30 sec intervals) produced slower propagation velocities and smaller numbers of spikes per burst at shorter stimulation intervals. These results suggest that the generation and propagation of spontaneous synchronous bursts in cultured cortical neurons is governed by the level of spontaneous presynaptic firing, by the degree of connectivity of the network, and by a distributed balance between excitation and recovery processes.

 

56.       N. Maeda, M. Kawashima, and Y. Horikoshi

            "Epitaxial-Growth Of Alas/Coal/Alas(001) Heterostructures By Controlling The Metal-Surface"

            J. Appl. Phys. 78 (10), 6013-6026 (1995).

 

            ABSTRACT: Epitaxial growth of CoAl films on AlAs(001) films was examined for films with Co contents of 47-58 at. %. The surface terminations of CoAl films were characterized, and the dependance of surface terminations and surface reconstructions on the Co/Al composition was examined. When AlAs/CoAl/AlAs heterostructures were fabricated by growing AlAs overlayers on CoAl films whose surface terminations were well defined, a mixture of AlAs(001) and AlAs(111) phases grew on the Al-terminated surface, whereas only the AlAs(001) phase grew on the Co-terminated surface. The Go-terminated CoAl surface thus is suitable for the overgrowth of AlAs. A high-quality epitaxial GaAs/AlAs/CoAl/AlAs/GaAs heterostructure was grown by combining the control of metal surface terminations with low-temperature migration-enhanced epitaxial growth of AlAs overlayers. (C) 1995 American Institute of Physics.

 

57.       T. Makimoto, B. Brar, and H. Kroemer

            "Hole Accumulation In (In)Gasb/Alsb Quantum-Wells Induced By The Fermi-Level Pinning Of An Inas Surface"

            J. Cryst. Growth 150 (1-4), 883-886 (1995).

 

            ABSTRACT: We demonstrate hole accumulation in unintentionally doped (In)GaSb/AlSb quantum wells, using an InAs surface as a cap layer. From the hole concentrations in quantum wells, the energy difference between the conduction band edge of InAs and the valence band edge of GaSb is estimated. Relatively high two-dimensional hole mobilities of 650 and 7000 cm(2)/V. s are obtained from Hall measurements at 300 and 77 K. For a strained InGaSb/AlSb quantum well, mobility enhancement is observed.

 

58.       T. Makimoto and N. Kobayashi

            "Sharp Photoluminescence Lines From Nitrogen Atomic-Layer-Doped Gaas"

            Appl. Phys. Lett. 67 (5), 688-690 (1995).

 

            ABSTRACT: We performed nitrogen atomic-layer doping into GaAs grown by molecular beam epitaxy using nitrogen molecules (N-2) cracked by a hot tungsten filament. While uniformly nitrogen-doped GaAs layers show relatively weak nitrogen-related photoluminescence lines, nitrogen atomic-layer-doped GaAs layers show a series of sharp and strong photoluminescence lines. The dominant photoluminescence line was observed at 1.4437 eV, where an exciton bound to the nitrogen isotropic traps has the highest binding energy. (C) 1995 American Institute of Physics.

 

59.       T. Makimoto and N. Kobayashi

            "Nitridation Of Gaas-Surfaces Using Nitrogen Through A Hot Tungsten Filament"

            Appl. Phys. Lett. 67 (4), 548-550 (1995).

 

            ABSTRACT: This letter reports the nitridation of GaAs surfaces using N-2 through a hot tungsten filament. After nitridation, GaAs cap layers were grown by molecular beam epitaxy to form GaAs/GaN/GaAs structures. For these structures, we determine the sheet nitrogen atom concentration by secondary ion mass spectrometry analysis. The sheet nitrogen atom concentration is proportional to the square root of the N-2 pressure, indicating that N-2 molecules are decomposed into nitrogen atoms to adsorb on the GaAs surfaces. The activation energy of this decomposition process is 3.6+/-0.4 eV. (C) 1995 American Institute of Physics.

 

60.       H. Murase and M. Lindenbaum

            "Partial Eigenvalue Decomposition Of Large Images Using Spatial-Temporal Adaptive Method"

            IEEE Trans. Image Process. 4 (5), 620-629 (1995).

 

            ABSTRACT: Finding eigenvectors of a sequence of real images has usually been considered to require too much computation to be practical. Our spatial temporal adaptive (STA) method reduces the computational complexity of the approximate partial eigenvalue decomposition based on image encoding, Spatial temporal encoding is used to reduce storage and computation, and then, singular value decomposition (SVD) is applied. After the adaptive discrete cosine transform (DCT) encoding, blocks that are similar in consecutive images are consolidated. The computational economy of our method was verified by tests on different large sets of images, The results show that this method is 6 to 10 times faster than the traditional SVD method for several kinds of real images, The economy of this algorithm increases with increasing correlation within the image and with increasing correlation between consecutive images within a set, This algorithm is useful for pattern recognition using eigenvectors, which is a research field that has been active recently.

 

61.       H. Murase and S. K. Nayar

            "3-Dimensional Object Recognition From Appearance - Parametric Eigenspace Method"

            Syst. Comput. Jpn. 26 (8), 45-54 (1995).

 

            ABSTRACT: Technology of recognizing a 3-dimensional object and finding its direction from a 2-dimensional image is important in practical applications such as classification of industrial products. A typical conventional method for this purpose uses the 3-dimensional structure of the object such as its edges and surface shapes. However, extraction of a 3-dimensional structure with a high accuracy, notably that of an arbitrary shaped object, is difficult. This paper proposes a method of recognizing a 3-dimensional object by using a 2-dimensional collation. A 2-dimensional collation which requires no 3-dimensional feature has never seriously been examined because it has been considered that the amounts of computation and a memory for learning the 2-dimensional image data (which are very complex due to the variations of viewing and lighting angles) are not acceptable. The proposed method can learn a 3-dimensional object as a set of 2-dimensional images by using a new parametric eigenspace approach with a small memory capacity. The proposed method can easily learn a 3-dimensional object from its 2-dimensional image, and can recognize the object and estimate its pose. This paper includes experimental comparisons between the proposed method and other 2-dimensional collation methods.

 

62.       H. Murase and S. K. Nayar

            "Visual Learning And Recognition Of 3-D Objects From Appearance"

            Int. J. Comput. Vis. 14 (1), 5-24 (1995).

 

            ABSTRACT: The problem of automatically learning object models for recognition and pose estimation is addressed. In contrast to the traditional approach, the recognition problem is formulated as one of matching appearance rather than shape. The appearance of an object in a two-dimensional image depends on its shape, reflectance properties, pose in the scene, and the illumination conditions. While shape and reflectance are intrinsic properties and constant for a rigid object, pose and illumination vary from scene to scene. A compact representation of object appearance is proposed that is parametrized by pose and illumination. For each object of interest, a large set of images is obtained by automatically varying pose and illumination. This image set is compressed to obtain a low-dimensional subspace, called the eigenspace, in which the object is represented as a manifold. Given an unknown input image, the recognition system projects the image to eigenspace. The object is recognized based on the manifold it lies on. The exact position of the projection on the manifold determines the object's pose in the image. A variety of experiments are conducted using objects with complex appearance characteristics. The performance of the recognition and pose estimation algorithms is studied using over a thousand input images of sample objects. Sensitivity of recognition to the number of eigenspace dimensions and the number of learning samples is analyzed. For the objects used, appearance representation in eigenspaces with less than 20 dimensions produces accurate recognition results with an average pose estimation error of about 1.0 degree. A near real-time recognition system with 20 complex objects in the database has been developed. The paper is concluded with a discussion on various issues related to the proposed learning and recognition methodology.

 

63.       M. Naito and H. Sato

            "Stoichiometry Control Of Atomic-Beam Fluxes By Precipitated Impurity Phase Detection In Growth Of (Pr,Ce)(2)Cuo4 And (La,Sr)(2)Cuo4 Films"

            Appl. Phys. Lett. 67 (17), 2557-2559 (1995).

 

            ABSTRACT: This letter describes a method to sense slight off-stoichiometry (less than 2%-3%) in the cation ratio [Cu/(Pr+Ce) or Cu/(La+Sr)] of atomic beam fluxes by detecting precipitated impurity phases on the surface using reflection high-energy electron diffraction during growth of T'-(Pr,Ce)(2)CuO4 and T-(La,Sr)(2)CuO4 films. The method is based on the facts that off-stoichiometry of fluxes inevitably produces precipitates of certain impurity phases on the surface in film growth of these oxides, and that the species of the impurity phases are solely determined by the type of off-stoichiometry; copper rich or lanthanoid rich. Furthermore, it has been found that it is possible to recover a precipitate-free surface, from a surface with precipitates produced by lanthanoid-rich deposition, by later flux readjustment, but it is difficult from a surface with precipitates produced by copper-rich deposition. (C) 1995 American Institute of Physics.

 

64.       J. Nakata, N. Jourdan, H. Yamaguchi, K. Takahei, Y. Yamamoto, and Y. Kido

            "Structural-Analysis Of Erbium Sheet-Doped Gaas Grown By Molecular-Beam Epitaxy, With Ion Channeling Followed By Monte-Carlo Simulation"

            J. Appl. Phys. 77 (7), 3095-3103 (1995).

 

            ABSTRACT:

65.       S. Nishida and T. Sato

            "Motion Aftereffect With Flickering Test Patterns Reveals Higher Stages Of Motion Processing"

            Vision Res. 35 (4), 477-490 (1995).

 

            ABSTRACT: A series of experiments was conducted to clarify the distinction between motion aftereffects (MAEs) with static and counterphasing test patterns (static and flicker MAEs). It was found that while the motion of higher-order structure, such as areas defined by texture, flicker, or stereoscopic depth, induces little static MAE, such motion reliably generates flicker MAE. It was also found that static and picker MAEs were induced in opposite directions for stimuli in which first- and second-order structures moved in opposite directions (compound graftings of 2f + 3 for 2f + 3f + 4f, shifting a half cycle of 2f). When the test was static, MAE was induced in the direction opposite to the first-order motion; but when the test was counterphasing, MAE was induced in the direction opposite to the second-order motion. This means that static MAE is predominantly induced by first-order motion, but that flicker MAE is affected strongly by second-order motion, along with first-order motion. The present results suggest that static MAE primarily reflects adaptation of a low-level motion mechanism, where first-order motion is processed, while flicker MAE reveals a high-level motion processing, where both first- and second-order motion signals are available.

 

66.       S. Nishida, J. Yanagi, and T. Sato

            "Motion Assimilation And Contrast In Superimposed Gratings - Effects Of Spatiotemporal Frequency"

            Invest. Ophthalmol. Vis. Sci. 36 (4), S56-S56 (1995).

 

            ABSTRACT:

67.       T. Nishida, K. Uwai, Y. Kobayashi, and N. Kobayashi

            "Phase diagram of GaAs (111)B surface during metal-organic chemical vapor deposition measured by surface photo-absorption"

            Jpn. J. Appl. Phys. Part 1 - Regul. Pap. Short Notes Rev. Pap. 34 (12A), 6326-6330 (1995).

 

            ABSTRACT: Using surface photo-absorption (SPA), are have investigated GaAs epitaxial growth on a (111)B substrate grown by metal-organic chemical vapor deposition (MOCVD). From reflectivity trace measurement and a comparison of SPA spectra from an MOCVD-grown surface and an MBE-grown surface, we find fast As desorption in MOCVD growth corresponding to the phase transition from an As-rich (2 x 2) like structure to a (root 19x root 19) like structure, and subsequent slow As desorption corresponding to the phase transition from the (root 19x root 19) like structure to a Ga-rich (1 x 1) like surface. We have also obtained a phase diagram with respect to the transition from the As-rich (2 x 2) like structure to the (root 19x root 19) like structure. Specular morphology and sufficient TMG decomposition in high temperature growth are attributed to partial desorption of As-trimers from As-rich (2 x 2) like surface.

 

68.       T. Nishikawa and N. Uesugi

            "Transverse Beam Profiles On Traveling-Wave Optical Parametric Generation In Ktiopo4 Crystals"

            J. Appl. Phys. 78 (11), 6361-6366 (1995).

 

            ABSTRACT: Transverse beam profiles on traveling-wave optical parametric generation in KTiOPO4 crystals pumped by short optical pulses are investigated. The transverse beam profile deformation and splitting due to the back-conversion in the traveling-wave parametric propagation process is clarified for the first time from experimental observations and calculations. The transverse beam profile becomes ring shaped when there is no walk-off and deforms by expanding to the walk-off direction when walk-off exists. The deformation of the profile can be reduced by using a short crystal or decreasing the pump intensity due to the subsequent reduction in back-conversion. However, in these cases, the conversion efficiency becomes very low (3%-4%). We can improve the conversion efficiency while keeping good transverse beam profiles by using the two-crystal beam overlapping technique. The optimum conditions for this technique are clarified through calculations and it is shown that conversion efficiency of more than 18% can be achieved when they are used. (C) 1995 American Institute of Physics.

 

69.       T. Nishikawa and N. Uesugi

            "Effects Of Walk-Off And Group-Velocity Difference On The Optical Parametric Generation In Ktiopo4 Crystals"

            J. Appl. Phys. 77 (10), 4941-4947 (1995).

 

            ABSTRACT:

70.       O. Niwa

            "Electroanalysis With Interdigitated Array Microelectrodes"

            Electroanalysis 7 (7), 606-613 (1995).

 

            ABSTRACT: This review discusses electroanalysis with interdigitated array (IDA) microelectrodes. The basic electrochemical properties of IDAs are presented along with a calculation of diffusion-controlled current and an example of generation collection voltammetry to clarify the advantages of IDA for electroanalysis. The fabrication procedures of metal and novel carbon based IDAs are also summarized because the fabrication of very small IDAs is advantageous for electroanalysis. Previously reported electroanalytical applications of IDAs are overviewed. Among them are the measurement of redox electron conduction and molecular diffusion in various films, various types of enzyme sensors and electrochemical switches, an example of highly sensitive and selective generation collection voltammetry, a new stripping analysis using self-induced redox cycling and the detectors for flow cells and liquid chromatography.

 

71.       O. Niwa, H. Tabei, B. P. Solomon, F. M. Xie, and P. T. Kissinger

            "Improved Detection Limit For Catecholamines Using Liquid-Chromatography Electrochemistry With A Carbon Interdigitated Array Microelectrode"

            J. Chromatogr. B-Biomed. Appl. 670 (1), 21-28 (1995).

 

            ABSTRACT: The detection limit of catecholamines can be lowered by using a carbon-based interdigitated array (IDA) microelectrode as a detector for liquid chromatography (LC). The IDA electrode is more sensitive than conventional glassy carbon electrodes due to the high current density caused by radial diffusion at each microband, and redox cycling between two microband arrays. Since the number of redox cycles increases at lower flow-rates, the carbon IDA is particularly useful for microbore LC. In an LC system with a l-mm microbore column and a carbon IDA electrode, the peak height of dopamine (DA) and DOPAC did not decrease with decreasing flow-rate because of this redox cycling. A low detection limit of 5 fg (32 amol) and 9.6 fg (57 amol) was obtained for DA and DOPAC due to the high current density and low background noise level (0.1 pA) at the carbon IDA electrode. The total charge generated by oxidizing DA at the anodic array was more than the value calculated by assuming that all the DA molecules were oxidized.

 

72.       T. Ogino, H. Hibino, and Y. Homma

            "Patterning-Assisted Control For Ordered Arrangement Of Atomic Steps On Si(111) Surfaces"

            Jpn. J. Appl. Phys. Part 2 - Lett. 34 (6A), L668-L670 (1995).

 

            ABSTRACT: We propose a novel technique for organizing steps on Si surfaces. Arrays of small holes are formed on Si(111) wafers misoriented toward [11 ($) over bar 2] by using conventional Si technology. The wafers are then annealed in an ultrahigh vacuum at about 1300 degrees C. During the hole filling-in process, steps on the surface are arranged regularly, and finally parallel step bands are ordered after the holes have completely disappeared.

 

73.       S. Pau, G. Bjork, J. Jacobson, H. Cao, and Y. Yamamoto

            "Microcavity Exciton-Polariton Splitting In The Linear Regime"

            Phys. Rev. B 51 (20), 14437-14447 (1995).

 

            ABSTRACT:

74.       K. Prabhakaran and T. Ogino

            "Characterization Of Termination Layer Of Sige System Through Signatures Of Si-O And Ge-O Species"

            J. Cryst. Growth 150 (1-4), 1020-1024 (1995).

 

            ABSTRACT: In this paper, we describe a novel method of employing the phenomenon of oxygen chemisorption for surface atom identification on a SiGe surface. On a clean Si(100). dosing 100 L O-2 (1 Langmuir = 1 s at 1 x 10(-6) Torr) at room temperature gives rise to peaks at 7 and 10.2 eV in ultraviolet photoelectron spectroscopy with He I excitation (HeI UPS) and O Is is observed at 532.3 eV in X-ray photoelectron spectroscopy (NPS). Corresponding spectra for Ge(100) are a single peak at 5.2 eV in HeI UPS and O 1s at 531.3 eV. These signature spectra of Si-O and Ce-O species have been effectively employed for unambiguous characterization of the termination laver of SiGe surfaces. Upon dosing at room temperature, on a sample prepared by depositing 5 Angstrom Ge on Si(100) at 500 degrees C, oxygen bonds with Ge atoms are forming GeO, exclusively. This indicates surface termination entirely by Ge atoms. Oxygen adsorption at room temperature, on a sample prepared by codeposition of Ge and Si (total 5 Angstrom) onto Si(100) at 550 degrees C, forms a mixed oxide suggesting a surface termination by both Gt and Si atoms.

 

75.       K. Prabhakaran and T. Ogino

            "Oxygen-Chemisorption As A Tool For Atom Discrimination In The Sige Termination Layer"

            Surf. Sci. 327 (3), L511-L514 (1995).

 

            ABSTRACT: This Letter describes a novel method of employing the phenomenon of oxygen chemisorption for atom discrimination in the SiGe surface termination layer. Formation of Si-O species on clean Si(100) gives rise to peaks at 7 and 10.2 eV in He I UPS and a peak at 532.3 eV in O Is XPS. Whereas Ge-O species on a Ge(100) surface exhibits a single peak at 5.2 eV in HeI UPS and a peak at 531.3 eV in O Is XPS. These signature spectra of Si-O and Ge-O species have been effectively employed for atom discrimination in the termination layer of SiGe surfaces. Upon dosing at room temperature, on a sample prepared by depositing 5 Angstrom Ge on Si(100) at 550 degrees C,oxygen bonds with Ge atoms forming GeO, exclusively. This indicates termination entirely by Ge atoms. Oxygen adsorption at room temperature, on a sample prepared by codeposition of Ge and Si (total 5 Angstrom) onto Si(100) at 550 degrees C, forms a mixture of Si-O and Ge-O species suggesting a surface termination by both Ge and Si atoms.

 

76.       K. Prabhakaran and T. Ogino

            "Oxidation Of Ce(100) And Ge(111) Surfaces - An Ups And Xps Study"

            Surf. Sci. 325 (3), 263-271 (1995).

 

            ABSTRACT: In situ and ex situ oxidation studies are carried out on Ge(100) and Ge(111) employing techniques of ultraviolet and X-ray photoelectron spectroscopy (UPS and XPS). In situ oxidation produces mainly GeO on both the surfaces. Ge 3d and 2p levels show a chemical shift of about 1.4 and 1.8 eV respectively corresponding to this oxide. GeO desorbs from the surface on annealing to 400 degrees C without undergoing any transformation. On exposing to air, a mixture of oxides consisting mainly of GeO and GeO2 are formed on both the surfaces. Ge 3d and 2p levels show a chemical shift of 3.2 eV for GeO2. The amount of GeO2 increases with increasing time of exposure to air. The spectral features of both the species have been identified by UPS and XPS. GeO2 can be selectively removed from the surface by rinsing the sample in warm water. Atomically clean surfaces of Ge have been achieved by thermally decomposing a thin oxide layer prepared ex situ by chemical means, similar to Ishizaka and Shiraki's method for Si. O 1s and O 2p spectra of Si-O and Ge-O species exhibit distinctly different binding energy values and this helps unambiguous assignment of the bonding partner.

 

77.       D. J. Rogers, Y. Maeda, and K. Takei

            "Compositional Separation In Co-Cr Based Thin-Film Magnetic Recording Media"

            Scr. Metall. Materialia 33 (10-11), 1553-1561 (1995).

 

            ABSTRACT: Since Co is ferromagnetic and Cr is not, compositional inhomogeneities are believed to play an important role in determining the magnetic and recording properties of Go-Cr based thin film magnetic recording media. By preferentially etching Go-enriched regions in a Co-Cr film we discovered a ''Chrysanthemum-like Pattern,'' suggesting the presence of very fine, periodic compositional variations within individual grains. Subsequent studies, including thermo-magnetic analysis, nuclear magnetic resonance and atom probe field ion microscopy revealed the existence of a Compositional Separation (CS) in these films, producing distinct Go-enriched and Cr-enriched compositional phases. More recently, neutron scattering experiments have provided evidence of a magnetic microstructure with features matching the scale of the Co-enriched regions. Further investigations of this phenomenon are expected to open up new areas of research in both magnetic recording and thin film metallurgy. We review our study of CS, explain control of the compositional distribution using film growth parameters and discuss possible origins of CS.

 

78.       D. J. Rogers, Y. Maeda, and K. Takei

            "Compositional Separation In Co-Mn Magnetic Thin-Films"

            J. Appl. Phys. 78 (9), 5842-5844 (1995).

 

            ABSTRACT: The compositional distribution in fee Go-Mn magnetic thin films was studied in order to examine the possibility of a compositional separation, similar to that observed previously in hcp Co-Cr thin film magnetic recording media, occurring in an fee alloy system. Spin-echo Co-59 NMR study of Co75Mn25 films revealed a change from a homogeneous compositional distribution in a film deposited at a substrate temperature (Ts) of RT to a compositionally separated state in a film deposited at a Ts of 300 degrees C. Vibrating sample magnetometry revealed an associated three-fold enhancement in saturation magnetization in the films deposited at a Ts of 300 degrees C, (C) 1995 American Institute of Physics.

 

79.       J. B. Roseborough and H. Murase

            "Partial Eigenvalue Decomposition For Large Image Sets Using Run-Length Encoding"

            Pattern Recognit. 28 (3), 421-430 (1995).

 

            ABSTRACT: Pattern recognition using eigenvectors is a recent active research area. Finding eigenvectors of a large image set, however, has been considered to require too much computation to be practical. We therefore propose a new method For reducing computation of the partial eigenvalue decomposition based on run-length encoding. In this method, called the constant regions method, spatial encoding is used to reduce storage and computation, then coeigenvectors are computed and later converted to eigenvectors. For simple images, and when the number of pixels in an image is much larger than the number of images, the resulting algorithm is shown to grow as the first power of the basic image dimension, rather than the fourth power as for conventional methods. For comparison, the power method, the conjugate gradient method, and a so-called direct method for computing the partial eigenvalue decomposition are also presented, and recommendations are given for when each method should be used. The advantage of the proposed method are verified by tests in which the first several eigenvectors are computed for sets of images having varying complexity. This algorithm is useful for a research area of pattern recognition using eigenvectors.

 

80.       E. Sano and Y. Horikoshi

            "Effect Of As Pressure On Se Delta-Doped In Gaas By Molecular-Beam Epitaxy"

            Jpn. J. Appl. Phys. Part 1 - Regul. Pap. Short Notes Rev. Pap. 34 (9A), 4627-4630 (1995).

 

            ABSTRACT: Using elementary Se as an n-type dopant, Se delta-doped GaAs films were grown on (001) GaAs substrates by molecular beam epitaxy. The results of secondary ion mass spectroscopy and capacitance-voltage measurement show that it is necessary to use adequate As pressure during Se deposition to form a sharp interface. The Se concentration in the films did not change monotonically and reached a maximum value followed by a minimum value as a function of Se deposition time. The Se incorporation rate decrease over long Se deposition time is probably caused by Se condensation on the surface to form more volatile molecules. A possible model of the Se-adsorbed surface is proposed by considering the reflection high-energy electron diffraction patterns.

 

81.       H. Sasaki, K. Karaki, M. Mitsunaga, and N. Uesugi

            "Holographic Motion-Picture - Theory And Observations"

            J. Lumines. 64 (1-6), 273-281 (1995).

 

            ABSTRACT: We develop a full density-matrix theory describing the holographic motion picture, the direct recording of a real moving image into an inhomogeneous spectrum of a medium using spectral hole burning. The main emphasis is on the time resolution of the movie. It is concluded that, with a frequency scan rate faster than the square inverse of the characteristic time of the event, the moving image is faithfully recorded, the only limiting factor being the bandwidth of the medium. From the numerical simulation, the ultimate time resolution of the order of nanosecond is achieved when the scan rate is above 5 x 10(16) Hz/s for a cryogenic Eu3+:Y2SiO5 crystal. An experimental demonstration of the movie was performed for this crystal.

 

82.       S. Sasaki, Y. Hirayama, and S. Tarucha

            "Hot-Electron Ballistic Transport In Small 4-Terminal N-Algaas/Ingaas/Gaas Structures"

            Jpn. J. Appl. Phys. Part 1 - Regul. Pap. Short Notes Rev. Pap. 34 (2B), 1351-1354 (1995).

 

            ABSTRACT: We have studied hot electron ballistic transport in small four-terminal structures fabricated by Ga focused-ion-beam implantation from AlGaAs/InGaAs/GaAs modulation doped material. We have determined the characteristics of negative bend resistance as a function of hot electron energy by analyzing the magneto-resistance data. We have found that the ballistic nature of hot electrons is progressively lost when the excess energy of hot electrons exceeds LO-phonon energy, although the effect is smaller than in structures fabricated from conventional AlGaAs/GaAs modulation doped material due to the difference in the electron-phonon coupling strength. We have also found that the collimation effect, which is related to the geometry of the electron emitter, is preserved for hot ballistic electrons.

 

83.       H. Sato, M. Naito, S. Kinoshita, T. Arima, and Y. Tokura

            "Effect Of Lattice Mismatch On Surface-Morphology Of (110) Thin-Films Of 214-Type Superconductors"

            Appl. Phys. Lett. 66 (4), 514-516 (1995).

 

            ABSTRACT:

84.       M. Sato

            "Plasma-Assisted Low-Pressure Metalorganic Chemical-Vapor-Deposition Of Gan On Gaas Substrates"

            J. Appl. Phys. 78 (3), 2123-2125 (1995).

 

            ABSTRACT: Cubic and hexagonal GaN films were grown on (001) GaAs substrates by plasma-assisted low-pressure metalorganic chemical vapor deposition using triethylgallium and nitrogen radicals. The GaN growth rate was lower than that of GaAs and it was enhanced by simultaneous supply of hydrogen radicals to the growing surface. Cubic GaN was grown epitaxially under Ga-rich conditions, and c-axis oriented hexagonal GaN was grown under N-rich conditions. (C) 1995 American Institute of Physics.

 

85.       M. Sato

            "Plasma-Assisted Mocvd Growth Of Gaas/Gan/Gaas Thin-Layer Structures By N-As Replacement Using N-Radicals"

            Jpn. J. Appl. Phys. Part 1 - Regul. Pap. Short Notes Rev. Pap. 34 (2B), 1080-1084 (1995).

 

            ABSTRACT: GaAs/GaN/GaAs thin-layer structures were grown by plasma-assisted low-pressure metalorganic chemical vapor deposition. GaN layers were formed by exposing the surfaces of GaAs epitaxial layers to nitrogen-radical fluxes. When the nitrogen amount exceeded that in one-monolayer-thick GaN, the GaN/GaAs interfaces deteriorated drastically. Low-temperature photoluminescence from the structures suggests that the two-dimensional growth of GaN is limited to one-monolayer thick and that the excess nitrogen atoms form GaN clusters in the underlying layers. The one-monolayer-thick GaN embedded in GaAs shows intense photoluminescence, whereas the GaN cluster is non-radiative, probably because of the defects caused by the large lattice-mismatch between GaN and GaAs.

 

86.       M. Sato

            "Effect Of Plasma-Generated Hydrogen Radicals On The Growth Of Gaas Using Trimethylgallium"

            Jpn. J. Appl. Phys. Part 2 - Lett. 34 (1B), L93-L96 (1995).

 

            ABSTRACT: The effect of hydrogen radicals on the metalorganic chemical vapor deposition of GaAs was investigated by introducing radicals using a downstream-type plasma-cracking cell. The hydrogen radicals enhanced the decomposition of trimethylgallium at the substrate surface. The increase in the growth rates with increasing radical flux at low temperatures, where growth was kinetically-controlled, and the reduction in carbon concentrations in GaAs grown at high temperatures with the addition of radicals were observed.

 

87.       H. Shibata, K. Semba, A. Matsuda, and T. Yamada

            "Infrared Reflectivity Of Untwinned Yba2(Cu1-Xznx)(3)O-7-Delta Single-Crystals"

            Phys. Rev. B 51 (14), 9294-9297 (1995).

 

            ABSTRACT:

88.       K. Shiraishi and T. Ito

            "Theoretical Investigation Of Adsorption Behavior During Molecular-Beam Epitaxy Growth Of Gaas - Ab-Initio Based Microscopic Calculation"

            J. Cryst. Growth 150 (1-4), 158-162 (1995).

 

            ABSTRACT: This paper investigates, theoretically, the migration potential and adsorption energies of Ga adatoms on a reconstructed As-rich GaAs (001)-(2 X 4) surface by ab initio calculation. The calculated results show that migration potential depends sensitively on the number of surface Ga adatoms and that the adsorption energy oscillates with the adsorption of every other atom. The dependence on the number of surface Ga atoms is explained by the effects of the surface distortion and the electron counting model. This paper also discusses As incorporation during epitaxial growth and demonstrates the dynamical behavior of Ga adatoms at finite temperature by Monte-Carlo simulation.

 

89.       Y. Shiraki

            "Homotopy Equivalent Spectral Transformation And Morse-Theory"

            IEICE Trans. Fundam. Electron. Commun. Comput. Sci. E78A (9), 1186-1191 (1995).

 

            ABSTRACT: The systematic treatment of speech-spectrum transformation can be obtained in terms of algebraic topology and Morse theory. Some properties of homotopy-equivalence in the transformation of 1- and 2-dimensional speech spectrum are discussed.

 

90.       J. M. Smith, P. C. Klipstein, D. G. Austing, R. Grey, and G. Hill

            "The Role Of Interface Quality In Resonant-Tunneling Between Transverse X-States In Gaas/Alas Double-Barrier Structures Pressurized Beyond The Type-Ii Transition"

            J. Phys. Chem. Solids 56 (3-4), 475-479 (1995).

 

            ABSTRACT: We examine in detail the first high pressure resonance related to tunneling between the lowest transverse X-state in each AlAs layer, of GaAs/AlAs 'double barrier' structures with equal AlAs thicknesses grown by Molecular Beam Epitaxy (MBE) calibrated using Reflection High Energy Electron Diffraction (RHEED), and we compare the results with previously reported measurements on Metalorganic Vapour Phase Epitaxy (MOVPE) grown structures. The resonance, which does not conserve in-plane momentum, is much sharper and more asymmetric between forward and reverse biases in MBE structures, and the sense of the asymmetry in these structures, which can be as large as 6:1, always appears to be the same relative to the polarity of the substrate. At the same time momentum conserving resonances, such as the ambient pressure Gamma-resonance, remain highly symmetric in all samples, confirming that the two AlAs layers have closely equal thicknesses. The lack of in-plane momentum conservation results in great sensitivity to differences in roughness at the two types of interface (AlAs grown on GaAs or GaAs grown on AlAs), and to differences in roughness related to the method of growth (MBE and MOVPE).

 

91.       T. Sogawa, S. Ando, and H. Kanbe

            "Lateral-Size Control Of Trench-Buried Quantum Wires Using Gaas/Alas Superlattice Layers"

            Jpn. J. Appl. Phys. Part 1 - Regul. Pap. Short Notes Rev. Pap. 34 (8B), 4405-4407 (1995).

 

            ABSTRACT: We demonstrated the lateral-size control of GaAs/AlAs trench-buried quantum wires (QWRs) in the region below 20 nm by using GaAs/AlAs superlattice layers (SLs). Scanning electron microscopy images and photoluminescence properties of the trench-buried QWRs revealed that the trench width can be controlled by varying the number of SLs and reduced to about 13 nm by growing 7 pairs of SLs. The GaAs wires in the trenches have a tendency to grow so as to maintain a constant cross-sectional area, which leads to reduction of the energetic broadening of the quantum sub-levels caused by pattern size fluctuation.

 

92.       T. Sogawa, S. Ando, and H. Kanbe

            "Photoluminescence Properties Of 13x13 Nm Gaas Quantum Wires Buried In Trench Structures Reduced By Growing Gaas/Alas Superlattice Layers"

            Appl. Phys. Lett. 67 (8), 1087-1089 (1995).

 

            ABSTRACT: We report lateral-size control of GaAs/AlAs trench-buried quantum wires (QWRs) on a scale of 10 nm by metalorganic chemical vapor deposition using nonplanar substrates. The lateral width is reduced to 12-13 nm by growing GaAs/AlAs superlattice layers (SLs) on the (110) sidewall facets of the trenches, where the roughness of the SL sidewalls is approximately several monolayers. Low-temperature photoluminescence (PL) properties of nearly square 13X13 nm QWRs buried in the trenches exhibit a strong PL blue shift of 85 meV with respect to the band-gap energy of GaAs bulk and PL polarization anisotropy of 25% due to two-dimensional quantum confinement effects. The emission from Ga-rich AlGaAs regions in the trenches constituting AlGaAs vertical quantum wells was also observed. We demonstrate that substituting GaAs/AlAs SLs for the AlGaAs layer effectively eliminates the undesired emission levels caused by the inevitable Al content fluctuation in the AlGaAs layer grown on nonplanar structures. (C) 1995 American Institute of Physics.

 

93.       K. Sumitomo, T. Nishioka, and T. Ogino

            "Ge Island Formation On Si(111) In Solid-Phase Epitaxy Studied By Medium-Energy Ion-Scattering"

            J. Vac. Sci. Technol. B 13 (2), 387-389 (1995).

 

            ABSTRACT:

94.       K. Sumitomo, T. Nishioka, N. Shimizu, Y. Shinoda, and T. Ogino

            "Interface Structure Of Ge/Si(111) During Solid-Phase Epitaxy Studied By Medium-Energy Ion-Scattering"

            J. Vac. Sci. Technol. A-Vac. Surf. Films 13 (2), 289-294 (1995).

 

            ABSTRACT:

95.       H. Suzuki, H. Meyer, S. Hoshino, and D. Haarer

            "Charge carrier and exciton dynamics in polysilane-based multilayer light-emitting diodes as monitored with electroluminescence"

            J. Lumines. 66-7 (1-6), 423-428 (1995).

 

            ABSTRACT: By using two modes of excitation, optical excitation and current excitation, we have clarified the device physics in operation of multilayer organic light-emitting diodes utilizing poly(methylphenylsilane) as a hole transporting material, focusing on the dynamics of charge carriers injected from electrodes and of excitons generated by the charge carrier recombination.

 

96.       H. Suzuki, H. Meyer, S. Hoshino, and D. Haarer

            "Electroluminescence From Multilayer Organic Light-Emitting-Diodes Using Poly(Methylphenylsilane) As Hale Transporting Material"

            J. Appl. Phys. 78 (4), 2684-2690 (1995).

 

            ABSTRACT: We have investigated the optical and electrical properties of polysilane-based multilayer electroluminescent (EL) devices, utilizing poly(methylphenylsilane) (PMPS) as the hole transporting material, in order to elucidate the mechanism of EL emission in these devices. The EL devices which we fabricated have two or three functional organic layers. These layers are composed of a PMPS layer as well as a 3-(2'-Benzothiazolyl)-7-diethylaminocoumarin (Coumarin 6) doped polystyrene (PS) layer and/or a tris-(8-hydroxyquinoline) aluminum (Alq(3)) layer. An indium-tin-oxide-coated glass and an Al electrode were used as the hole and the electron injecting electrode, respectively. On the basis of a combined analysis of the basic characteristics of these devices, photoexcited fluorescence spectra and decay curves as well as the band diagram of these devices, we concluded that the recombination of charge carriers and the EL emission in the three-layer device occur both in the Coumarin 6:PS and the evaporated Alq(3) layers. (C) 1995 American Institute of Physics.

 

97.       K. Suzuki, K. Saito, T. Saku, A. Sugimura, Y. Horikoshi, and S. Yamada

            "Electron-Distribution In Modulation-Doped Algaas/Gaas Single Quantum-Wells And Inverted Modulation-Doped Gaas/Algaas Heterostructures"

            J. Cryst. Growth 150 (1-4), 1266-1269 (1995).

 

            ABSTRACT: In high-electron-mobility modulation-doped single quantum wells and inverted heterostructures. electrons are confined not only at the main channel but also at the heterointerface an the substrate side. Cyclotron resonance absorption measurements were used to determine the electron distribution in these structures. A contribution to the overall conductivity by the electrons at the heterointerface on the substrate side was found.

 

98.       A. Taguchi and T. Ohno

            "Total energy calculation for Er impurity in GaAs"

            in Icds-18 - Proceedings Of The 18th International Conference On Defects In Semiconductors, Pts 1-4, Materials Science Forum Vol. 196- (Transtec Publications Ltd, Zurich-Uetikon, 1995), pp. 627-631.

 

            ABSTRACT: We calculated the total energy of Er point defects in GaAs and the coupled defects of Er with the native defects of GaAs by the ab initio pseudopotential method. The total energy calculation results suggest that an Er atom easily couples with the native defects of GaAs. This tendency may be the reason why the Er intra-4f-shell luminescence spectrum is complicated and strongly depends on sample preparation methods and growth conditions.

 

99.       A. Taguchi and K. Takahei

            "Estimation of rare-earth energy levels in the bandgap of semiconductors"

            in Icds-18 - Proceedings Of The 18th International Conference On Defects In Semiconductors, Pts 1-4, Materials Science Forum Vol. 196- (Transtec Publications Ltd, Zurich-Uetikon, 1995), pp. 633-637.

 

            ABSTRACT: We have applied an energy transfer model, which has been verified for Yb-doped InP system, to other rare-earth doped semiconductors such as Er-doped GaAs and Nd-doped GaP. By applying the model, the temperature dependence of the decay time of the 4f-shell luminescence can be calculated by using two parameters: the energy which has to be compensated for in the energy transfer process and the transition matrix element. The values of the parameters were determined by fitting of the calculated temperature dependence to the experimentally obtained one. The calculated temperature dependencies agree well with expert mental results, showing that an energy transfer mechanism in these materials is similar to that in InP:Yb. Using the estimated values of the parameters, the energy level positions in the bandgap for optically active rare-earth centers in these materials were estimated.

 

100.    K. Takahei, Y. Horikoshi, and A. Taguchi

            "Characteristics of Er-oxygen complex centers in GaAs"

            in Icds-18 - Proceedings Of The 18th International Conference On Defects In Semiconductors, Pts 1-4, Materials Science Forum Vol. 196- (Transtec Publications Ltd, Zurich-Uetikon, 1995), pp. 639-643.

 

            ABSTRACT: Er-doped GaAs was grown with oxygen codoping by metalorganic vapor phase epitaxy using an O-18 isotope. It was found that the Er center formed by reaction of Er and oxygen molecules, the Er-20 center, shows a sharp photoluminescence spectrum with strong intensity, while other centers formed by reaction of Er and residual oxygen complexes show only broad spectra with weak intensity. The intensity of the luminescence from the Er-20 center decreases when epitaxial layers were grown on (100) substrates misoriented towards [111]A or [111]B directions. A decrease was also observed when an epitaxial layer was grown at a lower growth rate. We speculate that the Er-20 center is formed only when an Er atom reacts with an oxygen molecule on an atomically flat (100) surface and becomes a core of an atomic-step island.

 

101.    K. Takahei and A. Taguchi

            "Photoluminescence Analysis Of Er-Doped Gaas Under Host Photoexcitation And Direct Intra-4f-Shell Photoexcitation"

            J. Appl. Phys. 78 (9), 5614-5618 (1995).

 

            ABSTRACT: Er-doped GaAs shows a sharp and simple intra-4f-shell luminescence spectrum of Er3+ ions under host photoexcitation, when the crystal is grown with deliberate oxygen codoping by metalorganic chemical-vapor deposition. Photoluminescence-excitation measurements by direct intra-4f-shell excitation, however, revealed that there are many kinds of Er3+ centers in the same crystal. To clarify the differences between these Er centers, photoluminescence was measured under both host photoexcitation and direct intra-4f-shell photoexcitation. It was found that there are three types of Er centers with distinctly different characteristics. The first type of Er center shows a sharp and simple photoluminescence spectrum with a high intensity under host photoexcitation. This center had been assigned as an Er atom coupled with two oxygen atoms (Er-Ga-20 center). The second type of Er center show sharp and simple spectra but only under direct intra-4f-shell photoexcitation and not under host photoexcitation. In a sample with Er concentration of 1.4X10(18) cm(-3), several such centers with distinctly different atomic configurations were found at substantial concentrations, probably exceeding that of the Er-Ga-20 center. As there is no intra-4f-shell luminescence for this type of center under host photoexcitation, no energy transfer path exists between the host and the 4f shells of this type of Er center. The third type of Er center shows complicated spectra even under intra-4f-shell photoexcitation with a specific photon energy. Analysis of photoluminescence spectra from this type of Er center revealed evidence of energy migration among Er3+ ions, suggesting that Er-rich aggregates are the origin of this type of PL spectra. Under host photoexcitation, this type of Er center shows luminescence but with a much lower intensity than the Er-Ga-20 center. The luminescence from Er centers similar to the third type probably is dominant in the PL spectrum of Er-doped GaAs grown without deliberate oxygen codoping, which does not contain an appreciable concentration of the Er-Ga-20 centers. (C) 1995 American Institute of Physics.

 

102.    K. Takahei and A. Taguchi

            "Photoluminescence Excitation Analysis Of Er-Doped Gaas Grown By Metalorganic Vapor-Phase Deposition"

            J. Appl. Phys. 77 (4), 1735-1740 (1995).

 

            ABSTRACT:

103.    K. Takarabe, T. Mizushima, S. Minomura, A. Taguchi, and K. Takahei

            "Pressure-induced increase of the intra-4f luminescence of GaAs:Er,O at room temperature"

            in Icds-18 - Proceedings Of The 18th International Conference On Defects In Semiconductors, Pts 1-4, Materials Science Forum Vol. 196- (Transtec Publications Ltd, Zurich-Uetikon, 1995), pp. 645-649.

 

            ABSTRACT: The pressure effect of the intra-4f luminescence from GaAs:Er,O is reported. The intra-4f luminescence is increased by a factor of two by applying pressure at room temperature. This result is attributed to the decrease of the so-called energy back-transfer from the excited state I-4(13/2) to the GaAs host.

 

104.    H. Takayanagi and T. Akazaki

            "Submicron gate-fitted superconducting junction using a two-dimensional electron gas"

            Jpn. J. Appl. Phys. Part 1 - Regul. Pap. Short Notes Rev. Pap. 34 (12B), 6977-6986 (1995).

 

            ABSTRACT: We fabricated submicron-gate superconducting junctions which are coupled with an InAs channel inserted in an InAlAs/InGaAs heterostructure. Electron beam lithography, and chemical and rf sputter etching techniques are used to fabricate a junction in the submicron range. The fabrication process of the junction is described in detail. The fabricated gate configuration shows high controllability of both the superconducting critical current and normal resistance of the junction using gate voltage. This provides a voltage gain of over 1 and enables the first demonstration as a Josephson field effect transistor. Moreover, new quantum phenomena, c.g., Fabry-Perot interference and quantization of critical current as well as focusing of Andreev-reflected holes in a quantum point contact, were observed. Junction characteristics from the viewpoints of both three-terminal operation and the new quantum phenomena are reported.

 

105.    H. Takayanagi and T. Akazaki

            "Temperature-Dependence Of The Critical-Current In A Clean-Limit Superconductor-2deg-Superconductor Junction"

            Solid State Commun. 96 (11), 815-819 (1995).

 

            ABSTRACT: The temperature dependence of the superconducting critical current I-c is studied fora newly fabricated three-terminal Josephson junction. The junction is coupled with a two-dimensional electron gas (2DEG) which satisfies the clean-limit condition l > xi(N) (where l is the mean free path and xi(N) is the normal coherence length of the semiconductor). In the clean-limit region, I-c increases as temperature decreases to 0.1 K. In the dirty-limit legion which is achieved by applying a high-gate voltage, I-c shows saturation and then decreases at low temperatures due to localization effects.

 

106.    H. Takayanagi and T. Akazaki

            "Andreev Reflection At The Superconductor-2-Dimensional-Electron-Gas Interface By A Quantum Point-Contact"

            Phys. Rev. B 52 (12), R8633-R8636 (1995).

 

            ABSTRACT: Andreev reflection in a split-gate-fitted superconductor-normal-metal-superconductor junction is studied with retro property of Andreev reflection. As the normal metal, the junction uses a two-dimensional electron gas (2DEG) in a semiconductor heterostructure in the ballistic-transport regime. The differential resistance-voltage characteristics, measured as a function of gate voltage, show a clear change from current-deficit to excess-current characteristics. This change is attributed to the Andreev-reflected holes being focused on the quantum point contact defined in the 2DEG by the split gate.

 

107.    H. Takayanagi and T. Akazaki

            "Critical-Current Oscillations Due To Interference Effects In A Clean-Limit Superconductor-2-Dimensional-Electron-Gas-Superconductor Junction"

            Jpn. J. Appl. Phys. Part 1 - Regul. Pap. Short Notes Rev. Pap. 34 (8B), 4552-4554 (1995).

 

            ABSTRACT: We have confirmed the effects of interference on the superconducting critical current of a gate-fitted superconductor-normal metal-superconductor junction in the clean limit. As the normal metal, the junction uses a two-dimensional electron gas (2DEG), which is well confined in an InAs-inserted-channel InAlAs/InGaAs heterostructure. The superconducting critical current is measured as a function of the gate voltage and shows oscillations as a function of the 2DEG carrier concentration. This oscillation is explained by the Fabry-Perot interference of the quasi-particles that undergo two normal reflections between two Andreev reflections.

 

108.    H. Takayanagi, T. Akazaki, and J. Nitta

            "Observation Of Maximum Supercurrent Quantization In A Superconducting Quantum Point-Contact"

            Phys. Rev. Lett. 75 (19), 3533-3536 (1995).

 

            ABSTRACT: We have confirmed the quantization of the critical current in a superconducting quantum point contact consisting of a split-gate superconductor-(two-dimensional electron gas)-superconductor junction. The critical current and conductance show stepwise changes as a function of the gate voltage. We also observed resonant structure resulting from quantum interference of quasiparticles at the step edge.

 

109.    H. Takayanagi, T. Akazaki, and J. Nitta

            "Interference Effects On The Critical-Current In A Clean-Limit Superconductor Normal-Metal Superconductor Junction"

            Phys. Rev. B 51 (2), 1374-1377 (1995).

 

            ABSTRACT:

110.    H. Takayanagi, T. Akazaki, J. Nitta, and T. Enoki

            "Superconducting 3-Termimal Devices Using An Inas-Based 2-Dimensional Electron-Gas"

            Jpn. J. Appl. Phys. Part 1 - Regul. Pap. Short Notes Rev. Pap. 34 (2B), 1391-1395 (1995).

 

            ABSTRACT: A newly fabricated three-terminal Josephson junction is coupled with an InAs-inserted-channel InAlAs/InGaAs heterostructure. The two-dimensional electron gas (2DEG) confined in the inserted InAs layer has a high mobility of 73890 cm(2)/V. s and a high sheet-carrier density of 1.98 x 10(12) cm(-2) at 4.2 K. The supercurrent flows through the 2DEG and can be controlled by gate voltage. The critical current and the normal resistance as a function of gate voltage are measured and the sheet-carrier density dependence of the critical current is obtained. The experimental results for this dependence are explained by the superconducting proximity effect theory and by the normal transport of the 2DEG.

 

111.    H. Takayanagi, J. B. Hansen, and J. Nitta

            "Localization Effects On The Critical-Current Of A Superconductor Normal-Metal Superconductor Junction"

            Phys. Rev. Lett. 74 (1), 162-165 (1995).

 

            ABSTRACT:

112.    H. Takayanagi, J. B. Hansen, and J. Nitta

            "Mesoscopic Fluctuations Of The Critical-Current In A Superconductor Normal-Conductor Superconductor"

            Phys. Rev. Lett. 74 (1), 166-169 (1995).

 

            ABSTRACT:

113.    Y. Tanaka, S. Kashiwaya, and H. Takayanagi

            "Theory Of Superconducting Quantum-Dot Under Magnetic-Field"

            Jpn. J. Appl. Phys. Part 1 - Regul. Pap. Short Notes Rev. Pap. 34 (8B), 4566-4568 (1995).

 

            ABSTRACT: Basic properties of the quantum dot structure, which is a normal region created inside superconducting matter on a subnanometer scale, are predicted theoretically. The bound states change dramatically as the number of the magnetic flux quanta changes by one. We have clarified the origin of the ''nearly midgap states'' by intuitive consideration based on the unified picture of interference of the quasiparticle proposed by Kashiwaya.

 

114.    S. Tarucha

            "Solid-State Devices And Materials - Foreword"

            Jpn. J. Appl. Phys. Part 1 - Regul. Pap. Short Notes Rev. Pap. 34 (2B), U1-U1 (1995).

 

            ABSTRACT:

115.    S. Tarucha, D. G. Austing, and T. Honda

            "Resonant tunneling single electron transistors"

            Superlattices Microstruct. 18 (2), 121-129 (1995).

 

            ABSTRACT: We use a modulation-doped double barrier heterostructure to fabricate a resonant tunneling single electron transistor. Irregular Coulomb blockade oscillations are observed when the gate voltage is swept to vary one-by-one the number of electrons in the dot close to 'pinch-off'. The oscillation period is not regular, and generally becomes longer as the electron number is decreased down to zero, reflecting the growing importance of electron-electron interactions and size quantization. Negative differential resistance associated with resonant tunneling through zero-dimensional states is pronounced for a dot holding just a few electrons. The temperature dependence of the Coulomb blockade oscillations and that for the negative differential resistance are not the same. This highlights the different effects of charging and resonant tunneling on the transport characteristics. (C) 1995 Academic Press Limited

 

116.    S. Tarucha, T. Honda, and T. Saku

            "Reduction Of Quantized Conductance At Low-Temperatures Observed In 2 To 10 Mu-M-Long Quantum Wires"

            Solid State Commun. 94 (6), 413-418 (1995).

 

            ABSTRACT: We observe a small but definite decrease in quantized conductance at low temperatures in 2 to 10 mum-long single-mode quantum wires. The temperature dependence is stronger in the longer wires. The conductance of the 2mum-long wire is nearly constant below a critical temperature, at which the thermal length becomes longer than the wire length, while that of the 5 and 10 mum-long wires decreases fairly monotonically with decreasing temperature. We will discuss the effect of mutual Coulomb interaction that is responsible for the change in quantized conductance observed as a function of temperature and wire length.

 

117.    K. Uwai and N. Kobayashi

            "Structural Transformation Of As-Stabilized Surfaces Caused By Ga-Deposition Detected By Time-Resolved Surface Photoabsorption"

            J. Cryst. Growth 150 (1-4), 101-106 (1995).

 

            ABSTRACT: Evolution of surface structures during conversion from various As-stabilized surfaces to Ga-stabilized ones is observed by surface photo-absorption. Desorption of As dimers parallel to [110] is observed during the structural change of c(4 x 4) and (2 x 4)gamma. The evolution of Ga- and As-related peaks is isolated in surface dielectric anisotropy spectra, which are determined using p- and s-polarized surface photo-absorption spectra during the conversion of (2 x 4)beta to a Ga-stabilized (4 X 2) surface.

 

118.    L. M. Weegels, T. Saitoh, and H. Kanbe

            "Dynamics Of Gaas-Surfaces Exposed To Argon And Hydrogen Electron-Cyclotron-Resonance Plasmas Observed By Real-Time Optical Reflection Spectroscopy"

            J. Appl. Phys. 77 (11), 5987-5994 (1995).

 

            ABSTRACT:

119.    L. M. Weegels, T. Saitoh, and H. Kanbe

            "Temperature-Dependent Dry-Cleaning Characteristics Of Gaas (111)B Surfaces With A Hydrogen Electron-Cyclotron-Resonance Plasma"

            Appl. Phys. Lett. 66 (21), 2870-2872 (1995).

 

            ABSTRACT:

120.    M. Weyers and M. Sato

            "A Comparison Of The Growth Of Gaas And Gap From Trimethyl-Gallium"

            Jpn. J. Appl. Phys. Part 1 - Regul. Pap. Short Notes Rev. Pap. 34 (2A), 434-441 (1995).

 

            ABSTRACT: In the growth of GaAs and GaP from trimethyl-gallium (TMG) significant differences are observed. At low growth temperatures, the GaP growth rate is lower than that of GaAs. Additionally, more car,on is incorporated into GaP than into GaAs. Mass spectrometric studies on methyl desorption from a substrate show that As and P differ in their ability to break the final Ga-carbon bond. The lower efficiency of P in breaking monomethyl-gallium (MMG) causes to the observed differences in the growth rates and carbon uptake. Based on the growth results and the mass spectrometric data on methyl desorption, a model of the reaction path leading to the decomposition of TMG and to the production of Ga is developed. This model includes the presence of dimethyl-gallium (DMG) in both a physi-sorbed (weakly bonded) state and a chemi-sorbed (strongly bonded) state as the Brat intermediate products in the decomposition of TMG.

 

121.    T. Yamada, H. Yamaguchi, and Y. Horikoshi

            "Evaluation Of The Highly Coherent Surface-Structure Of The Gaas (411)A Plane Using Scanning-Tunneling-Microscopy"

            J. Cryst. Growth 150 (1-4), 421-424 (1995).

 

            ABSTRACT: We have observed the surface structure of (411)A GaAs by atomically resolved scanning tunneling microscopy for the first time. A highly ordered structure of straight atomic rows stretching along the [01 $$($) over bar 1] direction was observed. The structure was found to be composed of two kinds of alternately arranged rows with different contrasts. From this image, a surface structure model was proposed. It was also indicated that the surface roughness of a (411)A surface must be smaller than that of a (100) surface due to the corrugated surface structure in the former case.

 

122.    E. Yamaguchi and M. R. Junnarkar

            "Discovery Of New Photoluminescence Effect Related To Deep Donor Levels In Si-Doped Alxga1-Xas And Microstructures"

            J. Phys. Soc. Jpn. 64 (7), 2656-2668 (1995).

 

            ABSTRACT: We have discovered a new type of photoluminescence (PL) effect in Si-doped AlxGa1-xAs and their microstructures including double delta-doped systems and superlattices. This PL appears with photon energies higher than the incident photon energy at low temperatures. Specifically, the photoexcitation with the energy being 0.2 eV below the gap energy produces the band-edge PL for AlxGa1-xAs (0.35 less than or equal to x less than or equal to 0.40). Neither the Anti-Stokes Raman effect, the Franz-Keldish effect nor the multiple photon effect have been proven to cause the present anomalous phenomena. Various studies of this luminescence as functions of temperature, Si concentration, the excitation power intensity and the excitation energy have revealed that this effect is strongly related to the deep donor levels in AlxGa1-xAs (x greater than or equal to 0.3). We have discussed a possible origin of this new phenomena.

 

123.    H. Yamaguchi, Y. Homma, and Y. Horikoshi

            "In-Situ Observation Of Phase-Transition And The Transition-Induced Step Bunching On Inas(001) Surfaces By Scanning Electron-Microscopy"

            Appl. Phys. Lett. 66 (13), 1626-1628 (1995).

 

            ABSTRACT:

124.    H. Yamaguchi and Y. Horikoshi

            "Unified Model For First-Order Transition And Electrical-Properties Of Inas (001) Surfaces Based On Atom-Resolved Scanning-Tunneling-Microscopy Imaging"

            J. Cryst. Growth 150 (1-4), 148-151 (1995).

 

            ABSTRACT: A unified model that explains two differences between InAs and GaAs (001) surfaces, phase transition and electrical properties, is proposed based on atom-resolved images obtained by scanning tunneling microscopy. The annealed InAs surface has much lower density of kinks in the dimer-vacancy rows than the annealed GaAs. This can be the origin both for strong lateral interaction, which causes the first order surface phase transition, and for low surface state density of the InAs (001) surface.

 

125.    H. Yamaguchi and Y. Horikoshi

            "Surface-Structure Transitions On Inas(001) And Gaas(001) Surfaces"

            Phys. Rev. B 51 (15), 9836-9854 (1995).

 

            ABSTRACT:

126.    H. Yamaguchi, T. Yamada, and Y. Horikoshi

            "Flattening Transition On Gaas (411)A Surfaces Observed By Scanning-Tunneling-Microscopy"

            Jpn. J. Appl. Phys. Part 2 - Lett. 34 (11A), L1490-L1493 (1995).

 

            ABSTRACT: We have studied the atomic structures of GaAs (411)A surfaces by using scanning tunneling microscopy, and have found that the surface flatness largely depends on the As coverage. In contrast to the As-rich surface, which has no flat (411)A terraces but has (311)A and (511)A microfacets, the As-deficient surface shows flat (411)A terraces with 0.07-nm-high monomolecular steps. The detailed analysis based on the observed atomic arrangements indicates that the flattening transition can occur because the electron counting rule is broken at all monomolecular steps on the As-deficient surface.

 

127.    J. Yanagi, S. Nishida, and T. Sato

            "Motion Assimilation And Contrast In Superimposed Gratings - Effects Of Orientation"

            Invest. Ophthalmol. Vis. Sci. 36 (4), S56-S56 (1995).

 

            ABSTRACT:

128.    R. Yano and N. Uesugi

            "Transition Frequency And Temperature Dependences Of Homogeneous Width Of Nd3+ Ion In Silicate Glass"

            Opt. Commun. 119 (5-6), 545-551 (1995).

 

            ABSTRACT: The homogeneous width of the F-4(3/2)(1) - I-4(9/2) transition of Nd3+ ions which were doped into pure silicate glass was measured by accumulated photon echoes between 1.6 and 44 K. The origin of the dephasing of the Nd3+ ions is attributed to the configurational changes peculiar to glass which are often modeled by the two-level systems (TLSs) and the Raman process with low-frequency vibrational modes of silicate glass. Besides the TLS dephasing process, the Raman process with low-frequency modes has been found to be transition frequency dependent, and the homogeneous width is larger on the higher transition frequency side. These increases in the homogeneous width are attributed to the increase in the elastic field interaction and the electron-phonon interaction, respectively. The transition frequency dependence of the homogeneous width can be explained by taking the positions of the host ions and the TLSs into account.

 

129.    R. Yano and N. Uesugi

            "Homogeneous Width Of Eu3+ In Silicate Glass-Fiber Measured By Accumulated Photon-Echoes"

            J. Lumines. 64 (1-6), 33-37 (1995).

 

            ABSTRACT: The homogeneous width in the D-5(0)-F-7(0) transition of Eu3+ in a pure silicate glass fiber was measured by accumulated photon echoes between 1.6 and 44 K. The homogeneous width is proportional to T-linear at T < 7 K and is proportional to T-2 at T > 7K. This temperature dependence can be explained by the configurational changes peculiar to glass (two-level systems) and by the Raman process with low-frequency vibrational modes of silicate glass (the rotations of SiO4 tetrahedra). The variation of the homogeneous width across the inhomogeneous profile was also observed at T < 4 K.

 

130.    A. Yoshigoe, K. Mase, Y. Tsusaka, T. Urisu, Y. Kobayashi, and T. Ogino

            "In-Situ Observation Of Silicon Hydrides An Si(100) Surfaces During Synchrotron-Radiation-Stimulated Si2h6 Gas-Source Molecular-Beam Epitaxy"

            Appl. Phys. Lett. 67 (16), 2364-2366 (1995).

 

            ABSTRACT: Silicon hydrides (SiHn) on the Si(100) surface during synchrotron-radiation (SR) stimulated Si2H6 gas source molecular beam epitaxy has been observed in situ at low temperatures (less than or equal to 400 degrees C), by means of infrared reflection absorption spectroscopy using CoSi2 buried metal layer substrates. At high temperatures (400 degrees C, 370 degrees C), SiH is a dominant surface species, while with temperature decrease from 275 to 50 degrees C, the number of SiH decreases, and, on the other hand, SiH2 and SiH3 appear and increase. This result explains the change of reflection high-energy diffraction pattern from 2X1 to 1X1. The SiH in the bulk network has not been observed. SR irradiation on the film at 140 degrees C after deposition shows that SiH2 and SiH3 are easily decomposed to SiH and that SiH decomposes much more slowly than SiH2 and SiH3. (C) 1995 American Institute of Physics.