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Present Status and New Challenges of Nitride Semiconductors for Advanced Electronic Devices
|Yasushi Nanishi , Tomohiro Yamaguchi|
Ritsumeikan University, 1-1-1, Noji-higashi, Kusatsu, Shiga 525-8577, Japan
AlGaN/GaN hetero-structure attracted much attention as a promising material system for high power and high frequency transistors. Remarkable progress in high power and high frequency operation has been made in the last 10 years. Power performances at high frequency obtained from this structure confirmed the high potential of this system and production of these devices for high frequency power amplifier has been started.
Focused attention on InN has been made as a material for even higher frequency operation with its high mobility, small effective mass, large inter-valley separation and large optical phonon energy. After new finding of InN narrow band gap, material parameters of InN have been totally revised including effective mass and non parabolicity coefficient. Using these revised material parameters, carrier transport in InN is re-estimated and even higher performances in high frequency operation have been predicted.
In spite of these remarkable physical potentials, almost no reports on experimental demonstration of InN electronic devices have been made so far. Main reason for this comes from poor quality of InN, band bending and accumulation of carriers at the surface.
In this talk, we will introduce newly developed RF-MBE growth method which made it possible to grow high-quality InN very reproducibly. This new growth method is composed of In-rich growth process and consecutive In droplet elimination by nitrogen radical beam irradiation (DERI) process. Then, the results on studies on ohmic and MIS contacts to InN will be shown. InN re-growth technology applied to AlGaN/GaN HFET will also be introduced and show possibility to make new type of functional device using large band offset between InN and other nitride semiconductor system.
This work was supported by the MEXT through Grant-in Aids for Scientific Research in Priority Areas “Optoelectronics Frontier by Nitride Semiconductor” #18069012 and Scientific Research (A) #21246004.
Presentation: Invited oral at E-MRS Fall Meeting 2009, Symposium C, by Yasushi Nanishi
See On-line Journal of E-MRS Fall Meeting 2009
Submitted: 2009-05-06 05:34 Revised: 2009-06-07 00:48