Electron properties in GaAs for the design of MM-wave IMPATTs

A very staightforward method has been developed to apply space-charge resistance measurements for determining the high-field drift velocity of electrons in GaAs. The breakdown voltages of the single-drift flat-profile IMPATT diodes used in these measurements justify the validity of well known ionization rates for still higher electric fields.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44547/1/10762_2005_Article_BF01009408.pd

High-performance GaAs/AlAs superlattice electronic devices in oscillators at frequencies 100–320 GHz

Negative differential resistance devices were fabricated from two epitaxial wafers with very similar GaAs/AlAs super-lattices and evaluated in resonant-cap full-height waveguide cavities. These devices yielded output powers in the fun-damental mode between 105 GHz and 175 GHz, with 14 mW generated at 127.1 GHz and 9.2 mW at 133.2 GHz. The output power of 4.2 mW recorded at 145.3 GHz constitutes a 50-fold improvement over previous results in the funda-mental mode. The highest confirmed fundamental-mode oscillation frequency was 175.1 GHz. In a second-harmonic mode, the best devices yielded 0.92 mW at 249.6 GHz, 0.7 mW at 253.4 GHz, 0.61 mW at 272.0 GHz, and 0.54 mW at 280.7 GHz. These powers exceed those extracted previously from higher harmonic modes by orders of magnitude. The power of 0.92 mW constitutes an improvement by 77% around 250 GHz. The second-harmonic frequency of 317.4 GHz is the highest to date for superlattice electronic devices and is an increase by 25% over previous results

D-band (110-170 GHz) InP gunn devices

This paper reports on the development of InP Gunn sources for operation in the D-band (110-170 GHz). n+-n-n+ structures with flat doping as well as graded doping profiles have been considered. Oscillations were obtained at 108.3 GHz from a 1 [mu]m structure with a uniform n doping of 2.5 x 1016 cm-3. The CW RF output power was 33 mW. A 1 [mu]m graded structure with an n doping increasing linearly from 7.5 x 1015 to 2.0 x 1016 cm-3 has resulted in 20 mW at 120 GHz and 10 mW at 136 GHz. These results are believed to correspond to a fundamental mode operation and represent the state-of-the-art performance from InP Gunn devices at these frequencies. This improvement in performance is attributed in part to a processing technique based on the use of etch-stop layers and InGaAs cap layers. An etch-stop layer allows low-profile mesas (2-3 [mu]m) and InGaAs cap layers help reduce the contact resistance, thus minimizing series resistances in the device. In addition, a physical model based on the Monte Carlo method was developed to aid in the design of structures for high frequency operation. Experimental results obtained from a 1.7 [mu]m Gunn device operating at W-band frequencies were used to estimate appropriate InP material parameters.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30504/1/0000133.pd

Active two-terminal devices as local oscillators for low-noise receiver systems at submillimeter wave frequencies

The power capabilities of three different two-terminal devices, GaAs IMPATT diodes, InP Gunn devices and GaAs TUNNETT diodes are evaluated. Two different selective etching technologies have been employed to fabricate devices on either a diamond heat sink or an integral heat sink. The reported RF power levels in fundamental mode are 20 mW at 120 GHz and 15 mW at 135 GHz for D-band GaAs IMPATT diodes, 21 mW at 120 GHz, 17 mW at 133 GHz and 8 mW at 155 GHz for D-band InP Gunn devices and up to 35 mW around 103 GHz for W-band GaAs TUNNETT diodes. Typical de to RF conversion efficiencies range from 0.9% up to over 4.0%. In second harmonic mode power levels of 0.25 mW at 223 GHz were measured from TUNNETT diodes and 0.4 mW at 220 GHz from a Gunn device. Die Leistungsfähigkeit dreier verschiedener Zweipolbauelemente, GaAs-IMPATT-Dioden, InP-Gunn-Bauelemente und GaAs-TUNNETT-Dioden, wird untersucht. Zwei unterschiedliche Herstellungsverfahren mit selektivem Ätzen wurden eingesetzt, um Bauelemente auf einer Diamant- bzw. integrierten Wärmesenke herzustellen. Hochfrequenzausgangsleistungen von 20 mW bei 120 GHz und 15 mW bei 135 GHz wurden mit GaAs-IMPATT-Dioden für das D-Band erzielt, 21 mW bei 120 GHz, 17 mW bei 133 GHz und 8 mW bei 155 GHz mit InP-Gunn-Bauelementen für das D-Band und bis zu 35 mW um 103 GHz mit GaAs-TUNNETT-Dioden für das W-Band. Typische Hochfrequenzwirkungsgrade lagen zwischen 0,9% und über 4%. Bei der ersten Oberwelle wurden mit TUNNETT-Dioden HF-Leistungen von 0,25 mW bei 223 GHz gemessen und 0,4 mW bei 220 GHz mit einem Gunn-Bauelement.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46116/1/202_2005_Article_BF01574916.pd

1.55-μm optical phase-locked loop with integrated p-i-n / HBT photoreceiver in a flexible development platform

A monolithically integrated p-i-n / HBT photoreceiver was successfully employed in a development platform for hybrid optical phase-locked loops (OPLLs). Despite loop delay compromises necessary for flexibility in component substitution, this OPLL development platform has demonstrated a hold-in range of 1.558 GHz and possible locking frequencies from 1.00 to 20.75 GHz © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 15:4–7, 1997.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/35040/1/2_ftp.pd