ICCCAS Invited Speaker

Hitoshi Aoki (SMIEEE)

Rohm Semiconductor, Japan

Biography: Dr. Hitoshi Aoki is a technical adviser at Rohm Co. Itd. Previously, he was a full time professor at Teikyo Heisei University and visiting professor at Gunma University in Japan. He has over 35 years of device modeling experience in electronic industries. Prior to his carrier with Universities, Dr. Aoki founded a modeling company, MoDeCH Inc. in 2002, where he is now an Executive Advisor. He had been working at some leading companies of electronics in both the U.S.A. and Japan including the ULSI Research Laboratory of Hewlett-Packard Laboratories U.S.A, Agilent Technology, and Hewlett-Packard Japan. He received the Ph.D. degree from the Tokyo Institute of Technology, Tokyo, Japan, in 2002. He authored and coauthored two books related to compact modeling and more than 130 technical papers. Dr. Aoki is a senior member of IEEE.
Speech Title: Frequency Dispersion Modeling based on Trapping Effect in AlGaN/GaN HEMTs
Abstract: GaN-channel heterostructure field-effect transistors (HFETs) have been extensively studied over the past two decades. This interest has been due to the excellent properties of the IIInitride material system, such as high electron saturation velocity, large critical electric field, and large polar 2-D electron gas (2DEG) concentration.
Frequency dispersion of the output conductance attributed to trapping phenomena. The frequency dispersion of the output conductance or transconductance was largely investigated in GaAs MESFET and III-V HEMTs during the past. It was also observed in AlGaN/GaN HEMTs and may be attributed to traps located in the GaN channel layer, at the AlGaN/GaN interface or at the surface area. Trapping of carriers are generally responsible of parasitic effects, such as the virtual second gate, which directly impacts the power amplifier characteristics, the noise properties, and the reliability of the devices.
In this research, frequency dispersion of transconductance and output conductance in AlGaN/GaN high electron mobility transistors is modeled. The model includes two voltage controlled current sources and a small-signal equivalent circuit. Trapping effects are taken into account with parasitic electrical networks including distributed time constants. The model has been verified with S-parameter measurements.