The state-of-the-art InP-based HEMTs Ankit Sharma ECE695 20
Feb, 2015
Slide 2
Brief History Proposed by Takashi Mimura (Fujitsu Ltd) in 1979.
N-type AlGaAs layer thickness varied
Slide 3
Why InP based HEMTs ? GaAs-based HEMT InP-based HEMT e - in
InP-based HEMT: lower effective mass, hence higher mobility High
saturation velocity High electron concentration InP-based HEMTs
Higher Speed !
Slide 4 2.7 mS/um." ieee international electron devices
meeting, washington dc, december 5-7, 2011."> 2.7
mS/um.">
III-V HEMT : record f T vs time fT=688 GHz and fmax=800 GHz in
Lg=40 nm In0.7Ga0.3As MHEMTs with gm,max>2.7 mS/um." IEEE
International Electron Devices Meeting, Washington DC, December
5-7, 2011.
Slide 5
2004 : Shinohara Keisuke and Matsui Toshiaki Gate length <
50 nm T-shaped gate electrode (using Electron Beam Lithography)
Enables reduction of gate length while maintaining a large cross-
sectional area to minimize the gate resistance. TEM cross-section
of T-shaped gate |h 21 | 2 (dB) Freq (GHz) SHINOHARA, Keisuke, and
Toshiaki MATSUI. "3-7 Nano-Gate TransstorWorld's Fastest InP-HEMT."
Journal of the National Institute of Information and Communications
Technology 51 (2004): 95-102.
Slide 6
2007 : Northrop Grumman Space Tech., CA Gate length < 50 nm
Proposed a number of process enhancements Reduction of ohmic
contact resistance through a higher doped cap layer design coupled
with InAs/InGaAs channel grown by MBE. Sheet resistance of
epitaxial layers is lowered to 75 ohm/sq. (compared to 110 ohm/sq.
earlier) Mobility improved to 15000 cm 2 /V.sec (compared to 12000
cm 2 /V.sec) Fig 3. Calculated Fmax Lai, R. ; Northrop Grumman
Space Technol., Redondo Beach, Electron Devices Meeting, pp. 609-
611, 2007. IEDM 2007. IEEE International
Slide 7
2007 : Y. Nakasha et.al (Fujitsu) T-shaped gate suffers with
poor physical strength at the junction between a large top and
narrow stem. Proposed Y-shaped gate structure. Results in high
yield. Use BCB (Benzocyclobutene) as inter-layer dielectric to
achieve low dielectric constant (2.8) along with cavity around gate
for enhancing speed. Results in a speed gain of about 14% Kawano,
V. Yasuhiro Nakasha V. Yoichi, V. Masaru Sato, and V. Tsuyoshi
Takahashi V. Kiyoshi Hamaguchi. "Ultra high-speed and ultra
low-noise InP HEMTs." Fujitsu Sci. Tech. J 43.4 (2007):
486-494.
Slide 8 2.7 mS/um." ieee international electron devices
meeting, washington dc, december 5-7, 2011."> 2.7
mS/um.">
F T = 688 GHz ; F MAX = 800 GHz 2011 : Jess A. del Alamo (MIT)
fT=688 GHz and fmax=800 GHz in Lg=40 nm In0.7Ga0.3As MHEMTs with
gm,max>2.7 mS/um." IEEE International Electron Devices Meeting,
Washington DC, December 5-7, 2011.
Slide 9
F T = 850 GHz ; F MAX = 1.42 THz 25 nm gate-stem, 30 nm gate
length Also enable frontside and backside feature scaling to
increase speed. 2014 : Northrop Grumman Space Tech., CA Deal, WR. ;
Northrop Grumman Space Technol., Redondo Beach, Infrared,
Millimeter, and Terahertz waves (IRMMW-THz), 2014 39th
International Conference, pp 1-3, Sept 2014