Friday, June 15, 2007, 11:00am: “Fluoride-Based Plasma Treatment for Enhancement-mode III-Nitride HEMTs,” by Prof. Kevin Chen, BRK 1001
ABSTRACT: The recent discovery of the potential and charge modulation by
fluoride-based plasma treatment in III-nitride Heterojunction FETs
has opened up numerous new opportunities of enhancing device
performance and fabricating integrated circuits with preferable
circuit configurations. The most significant development based on the
fluorine treatment is the realization of self-aligned enhancement-
mode (E-mode) AlGaN/GaN HEMT (high electron mobility transistors)
that exhibits threshold voltages as high as +1 V, the complete turn-
off of the device at zero gate bias, low on-resistance and low knee-
voltage. In this talk, I will give a comprehensive overview of the
fluorine plasma treatment technique. Underlying physical mechanisms
will be discussed, together with detailed dc and RF device
characteristics. Examples of circuit applications based on monolithic
integration of enhancement-/depletion-mode (E/D-mode) HEMTs will also
be presented, including DCFL (direct-coupled FET logic) inverters and
ring oscillators operating up to 375oC, E/D-mode dual-gate HEMTs with
gain enhancement. Extensions of the fluorine treatment technique to
planar integration and enhancement-mode metal-insulator-semiconductor
HFET (MISHFET) will also be discussed.
BIO: Dr. Chen received a B.S. degree in Electronics from Peking University
in 1988 and the PhD degree in Physics from University of Maryland,
College Park, USA, in 1993. From January 1994 to December 1995, he
was a research fellow engineer in NTT (Nippon Telegraph and
Telephone) LSI laboratories, Atsugi, Japan, engaging in the research
and development of functional quantum effect devices and
heterojunction FET's (HFET's). In particular, he developed the device
technology for monolithic integration of resonant tunneling diodes
and HFETs on both GaAs and InP substrates, for applications in ultra-
high speed signal processing and communication systems. He also
developed the buried-Pt gate technology, which is widely used for
GaAs-based or InP-based enhancement-mode HEMT and PHEMT
implementations. From 1996 to 1998, he was an assistant professor in
the Department of Electronic Engineering, City University of Hong
Kong, carrying out research on high-speed device and circuit
simulations. Dr. Chen then joined the wireless semiconductor division
of Agilent Technologies, Inc. (formerly Hewlett-Packard Co.), Santa
Clara, California, in 1999 working on RF power amplifiers used in
dual-band GSM/DCS wireless handsets. Dr. Chen joined HKUST in
November 2000, where he is currently an associate professor in the
Department of Electronic and Computer Engineering. At HKUST, his
current interests include high-speed semiconductor devices, RF/
microwave circuit designs, III-nitride devices for high-temperature
and high-voltage applications. Prof. Chen has authored or co-authored
more than 150 publications in international technical journals and
conference proceedings. Prof. Chen is a senior member of IEEE.
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