Materials Design Division
Physics of Electronic Materials
- Senior Assist. Prof. Tomoyuki TANIKAWA
- Assist. Prof. Takashi HANADA
- Assist. Prof. Shigeyuki KUBOYA
Creation of Innovative Energy-Saving Devices by Development of Crystal Growth Technology and Control of Physical Properties of Nitride Semiconductors
Our target is to develop new electronic materials which can open up novel device applications. The material of our current interest is a nitride semiconductor, lnGaAIN system, which is well known as a material for blue light-emittingdiodes (LEDs). Taking advantages of our epitaxial growth reactors developed by ourselves and a series of device fabrication equipment, we are going toward the further contribution to the global societies in terms of the energy saving, by developing high-power electronic devices and high-efficiency light-emitting devices.
It has been a major problem of the signifi cant energy loss in the recent accelerated applications to the electric vehicles and smart grid systems. The cause is clear that the low efficiency in the current switching devices on the inverters and power conditioners. We are aiming to develop nitrogenpolar inverted-channel high electron mobility transistors, which are expected to have much lower energy loss that that of conventional group-III-polar devices, in order to contribute to the global societies in terms of the promotion for further energy saving.
nitride semiconductors, epitaxial growth, electronic devices, light emitting devices
Figure 1: Polarity of GaN. The N-polar (0001) orientation has the reversed polarization, which allows us to explore a novel device design.
Figure 2: Schematic structures of high electron mobility transistor (HEMT): (a) group-III-polar conventional HEMT and (b) N-polar inverted HEMT.
Figure 3: a) Schematic structure of N-polar GaN/Al0.4Ga0.6N/ GaN HEMT. b) ID-VDS characteristics of N-polar MIS-gate and recess MIS-gate HEMT on sample shown in Figure 3a. We have demonstrated a prototype N-polar GaN Metal-Insulate- Semiconductor-gate HEMT (MIS-HEMT) with a promising device characteristics. These results obtained here open the window to the development of an N-polar HEMT for next generation high frequency and high power device.