Faculty Candidate Seminar
InAs-based Heterostructures for High Frequency, Low Power Components
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The unique material properties of InAs include a small electron effective mass (0.023me), high electron mobility (up to 30,000 cm2/V-s at 300K in 2DEG structures), infrared energy gap (3.5um), and a lattice parameter (6.058A) that is close to the lattice parameters of GaSb (6.095A) and AlSb (6.138A). We have exploited these properties to develop a wide range of InAs-based optoelectronic and electronic devices during the past decade, including: infrared lasers and detectors, avalanche photodiodes, resonant interband tunneling diodes, low voltage Schottky diodes, InAs-channel HEMTs, low Vbe HBTs, millimeter-wave detector diodes, and even Rashba spin filter devices.
In this seminar, I will focus on our recent development of electronic devices and circuits utilizing InAs-based heterostructures. In particular, I will emphasize the development of InAs-channel HEMT devices with ft > 300 GHz, targeting low power, low noise amplifier components needed for millmeter-wave radiometers. These device structures are grown by molecular beam epitaxy using metamorphic buffer layers on InP or GaAs semi-insulating substrates. The buffer layer lattice-parameter has been engineered to provide a strain-balanced configuration between the AlInAs barrier layers and the InAs channel layer. High peak gain is achieved in devices with 70nm gate lengths, with peak extrinsic gm=1.6 S/mm at Vds=0.7V and 1.2 S/mm at Vds=0.4V. Impact ionization effects are mitigated through careful tailoring of the device band edge diagram to ensure low output conductance and operation to reasonable drain-source voltages.
David H. Chow received the B.S. degree in applied physics at Case Western Reserve University in 1984, and the M.S. and Ph.D. degrees in applied physics from the California Institute of Technology in 1986 and 1989, respectively (where he was awarded the Milton and Francis Clauser Award for the most significant and original Ph.D. thesis). He joined HRL Laboratories in Malibu, CA in 1990, where he is currently a Department Manager and Senior Scientist. His research has focused on the growth and characterization of III-V semiconductor heterostructures and superlattices for electronic and optoelectronic device applications. These efforts have included: studies of GaInSb/InAs superlattices for infrared detection, the development of InAs/GaSb/AlSb and InGaAs/AlAs tunneling diodes for integrated circuits and RF detectors, investigations of superlattice-based 2-5 µm laser diode structures, the development of advanced sensors and controls for III-V molecular beam epitaxy, and the development of InAs-based heterojunction bipolar transistors and high electron mobility transistors. He has authored or co-authored more than 140 technical papers and holds 14 patents.