Overview of Quantum Electron Physics Research

Naoshi Uesugi
Physical Science Laboratory

　In the quantum electron physics field, based on ultra-small semiconductor structures fabricated by high-quality semiconductor crystal growth and advanced device fabrication techniques, our research focuses on single-electron control, new electron transport mechanisms and wide-bandgap semiconductor physics with the aim of developing innovative semiconductor devices. The Quantum Solid State Physics Research Group and Wide-Bandgap Semiconductor Research Group are working in the following areas.

Quantum Solid State Physics Research Group
(1)Electron properties in low-dimensional semiconductor heterostructures (two dimensional carrier transport and correlation effects in high-mobility semiconductors, fractional quantum Hall effect in two-dimensional hole systems, and cyclotron resonance in low dimensional semiconductors)
(2)Single-electron control in quantum dot systems (electronic properties of semiconductor artificial atoms and molecules, state control of electrons in coupled quantum dots by electromagnetic waves and magnetic fields, and fundamental properties leading to solid-state quantum computers using artificial molecules)
(3)Controlled semiconductor-surface crystal growth (heterostructure growth mode on high- index crystal surfaces and application to novel electron devices, and observation of electronic states by low-temperature STM)

Wide-Bandgap Semiconductor Research Group
(1)High-quality GaN crystal growth (mechanisms of GaN crystal growth by MOCVD, high-concentration p-type doping, and device processing technology)
(2)Facet growth mechanism (GaN facet growth mechanism, InP compound semiconductor facet growth mechanism, and their applications for surface emitting devices)
(3)GaN semiconductor device physics (electronic and optical properties of GaN quantum well structures, high temperature electron devices, and short-wavelength light emitting devices)
(4)Crystal growth technology under low gravity (high-quality InGaAs compound crystal growth in low gravity)

Major results obtained in this fiscal year are the observation of artificial molecular-like states in coupled quantum dot systems, the achievement of high-quality heterostructure crystal growth on (111)A surface in large lattice mismatch systems and its application to hot-electron transistors, demonstration of GaN ultraviolet light emitting diodes, and GaN HFET with superior high-temperature characteristics attained by high-quality GaN crystal growth and device processing technologies.

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