Overview of Device Physics Research


Katsumi Murase

Device Physics Laboratory


As history proves, innovative devices and materials can give rise to new industries, which then bring about changes in our social and private lives. In this context, the Device Physics Laboratory is responsible for creating novel electron devices indispensable for the technological foundation on which our society can continue to enjoy sustainable growth. This is also consistent with NTT's role of contributing to the progress of society by providing people with a variety of information sharing services.


To accomplish our mission, we have been engaged mainly in

(1) research on the physics and technology of novel electron devices, and

(2) research on new materials and integrated nanostructures that are expected to lead to the invention of devices based on new operating principles.


Currently, our target device is the single-electron device. This is regarded as the ultimate low-power device because it can operate under the control of only one electron. By employing single-electron devices for various information-processing and communication instruments, we will be able to overcome an energy crisis which would otherwise confront us as a result of an explosive increase in the use of such instruments in the future. Single-electron devices can therefore be said to be a key to the progress of our society.

The development of silicon (Si)-based single-electron devices is being undertaken by the Silicon Nanodevices Research Group, which is now focusing on how to create more complicated functions using a simpler device structure and how to establish a fabrication process suitable for extremely-large-scale integration of single-electron devices. To provide a guiding principle for the experimental work, theoretical studies on electron transport and thermal oxidation of Si nanostructures are also being carried out.

Fabrication of single-electron devices relies on nanofabrication technology, which is being investigated by the Nanostructure Technology Research Group. Electron-beam lithography and related resist-material processing are of central importance to the nanofabrication technology. This research group is also in charge of developing methods for precisely measuring the shape of nanostructures.

An alternative to artificial electron-beam lithography for creating nanostructures is natural self-assembling of atoms. To make the best use of this phenomenon, however, we have to contrive methods for positioning the nucleation sites at will. One method proposed by the Surface Science Research Group exploits atomic steps regularly arranged by using a lithographically pre-defined pattern on the whole surface of a Si wafer. The group is expanding the potential of this method on the basis of knowledge acquired by studying the atom dynamics on Si surfaces.

Novel operating principles of devices often have their roots in the properties of new materials. To synthesize materials with desirable properties, we should first be able to characterize the spatial and electronic structure of materials on the atomic scale. The Synchrotron Radiation Based Materials Research Group has been exploring analysis methods for this purpose utilizing synchrotron-radiated light, and is trying to make full use of those methods to create new materials.