M. Lui

112-GHz, 157-GHz, and 180-GHz InP HEMT traveling-wave amplifiers

We report traveling-wave amplifiers having 1-112 GHz bandwidth with 7 dB gain, and 1-157 GHz bandwidth with 5 dB gain. A third amplifier exhibited 5 dB gain and a 180 GHz high-frequency cutoff. The amplifiers were fabricated in a 0.1-/spl mu/m gate length InGaAs/InAlAs HEMT MIMIC technology. The use of gate-line capacitive-division, cascode gain cells and low-loss elevated coplanar waveguide lines have yielded record bandwidth broad-band amplifiers.

Very low noise and low power operation of cryogenic AlInAs/GaInAs/InP HFET's

The cryogenic performance of 0.15 /spl mu/m gate length AlInAs/GaInAs/InP devices is reported. A noise temperature of less than 10 K (less than five times over quantum limit hf/k) is demonstrated at 40 GHz with a power consumption of less than 0.6 mW under optimal noise bias condition. With about 5 K penalty in noise performance at 40 GHz, the devices could be operated with as little as 60 /spl mu/W total power consumption. An interpretation of the measured noise performance with the help of a noise model, room temperature S-parameters and DC characteristics (measured at room and cryogenic temperatures) is offered.<<ETX>>

Ka/Q-band doubly balanced MMIC mixers with low LO power

An InP-based broadband double-balanced mixer was developed having interchangeable RF/LO-ports and covering frequencies from 30 to 45 GHz, with a conversion loss of 12/spl plusmn/2 dB at the low LO power of 4 dBm. This broadband characteristic was achieved through the use of side-coupled baluns for both the RF and LO ports. The ring quad-diodes used state-of-the-art superlattice layers, which provided good control of turn-on voltage and were monolithically integrable with in-house HEMTs and HBTs. The diodes exhibited a very low turn-on voltage of 0.15 V at 1 mA, low series resistance, and high cutoff frequencies.

Fabrication of a 80 nm self-aligned T-gate AlInAs/GaInAs HEMT

The authors report on the fabrication and characterization of a high-performance 80-nm self-aligned T-gate AlInAs/GaInAs high electron mobility transistor (SAGHEMT). The 80 nm*50 mu m devices reported exhibit good pinchoff characteristics, high transconductance (g/sub m/=1150 mS/mm), low output conductance (g/sub ds/=120 mS/mm at RF), and state-of-the-art current gain cutoff frequency (f/sub T/=250 GHz). Modeling and analysis indicate that it is possible to significantly improve the performance of AlInAs/GaInAs SAGHEMTs by further reducing the gate length and/or optimizing the device structure.<<ETX>>

Rare earth doped fluoride waveguides fabricated using molecular beam epitaxy

We have grown planar waveguides of rare earth doped single crystal fluoride films on insulating and semiconductor substrates using molecular beam epitaxy and have formed channel waveguides by ion milling. Structural and spectral analysis demonstrates that excellent crystallinity is being achieved and that the rare earth ion is incorporated into the film at sites and in charge states similar to bulk laser hosts. Lifetime measurements confirm that the local environment of the dopant ion is essentially that found for bulk materials. Single and higher order optical mode propagation has been demonstrated for the channel waveguides. By exciting individual channels with an 800 nm pump, we have generated strong upconversion fluorescence in Er and Nd doped guides. The ability to fabricate these waveguides On semiconductor substrates substantiates the potential for on chip integration of both IR downconversion lasers and IR pumped upconversion visible and UV lasers with a diode laser pump source. The use of transition metal dopants is possible and would enable tunable operation. Waveguide propagation loss in present devices must be reduced to realize a laser oscillator and we discuss how this is being addressed. >

InP-based HEMT's with Al/sub 0.48/In/sub 0.52/As/sub x/P/sub 1-x/ Schottky layers

In this letter we report on the DC and RF performance of InP-based HEMTs with Al/sub 0.48/In/sub 0.52/As/sub x/P/sub 1-x/ Schottky layers and GaInAs/InP composite channels. By replacing the Al/sub 0.48/In/sub 0.52/As Schottky layer with Al/sub 0.48/In/sub 0.52/As/sub x/P/sub 1-x/ we have been able to increase the bandgap of the Schottky layer and achieve record breakdown voltages for 0.15 /spl mu/m gate-length InP-based HEMTs. The 0.15 /spl mu/m gate-length HEMTs have gate-to-drain breakdown voltages of over 13 V with current densities of 620 mA/mm and maximum transconductances of 730 mS/mm. On a wafer with a higher sheet charge we have obtained gate-to-drain breakdown voltages of 10.5 V with current densities of over 900 mA/mm. These are the highest breakdown voltages reported for 0.15 /spl mu/m gate-length InP-based HEMTs with such high current densities. At 10 GHz a 450 /spl mu/m wide HEMT has demonstrated 350 mW (780 mW/mm) of output power with power-added efficiency of 60% and 12 dB gain.<<ETX>>

Millimeter-wave waveguide-bandwidth cryogenically-coolable InP HEMT amplifiers

The design, construction and performance of 65-90 GHz and 75-110 GHz low-noise cryogenically-coolable amplifiers are presented. A comparison between modeled and measured performance is shown. A laboratory receiver exhibiting an average noise of 50 K across 65-90 GHz and 70 K across 75-110 GHz is described. These are the widest band and lowest noise HEMT receivers ever reported at these frequencies.

Q- and E-band cryogenically-coolable amplifiers using AlInAs/GaInAs/InP HEMTs

Design, construction and performance of several cryogenically-coolable millimeter-wave amplifiers for radio astronomy applications, using AlInAs/GaInAs/InP HEMTs, are presented. The examples include a 40-50 GHz amplifier with an average noise temperature of about 15 K and a 60-80 GHz amplifier yielding a laboratory receiver noise temperature of 37 K at 60 GHz and 50 K at 75 GHz.<<ETX>>

Manufacturability of 0.1- mu m millimeterwave low-noise InP HEMTs

Reports on the manufacturability of state-of-the-art passivated 0.1- mu m low-noise InP HEMTs (high electron mobility transistors). These HEMTs offer an attractive, cost-effective solution to millimeter-wave satellite communications. The authors discuss their yield and reproducibility, as well as typical performance at V- and W-bands.<<ETX>>

High-performance microwave power AlInAs/GaInAs/InP double heterojunction bipolar transistors with compositionally graded base-collector junction

We report, for the first time, on the use of compositional grading at the base-collector (B-C) junction of AlInAs/GaInAs/InP double heterojunction bipolar transistors (HBT) to achieve high-performance devices for microwave power and analog circuit applications. To overcome the conduction band potential barrier at the B-C junction, we have inserted an n-GaInAs spacer and a novel 100 nm compositional grade between the GaInAs base and the wide bandgap InP Collector. A base-collector breakdown voltage of 32 V, collector-emitter breakdown voltage of 26 V, and a f/sub max/ of 93 GHz have been achieved. Preliminary power measurements at 10 GHz on 240 /spl mu/m/sup 2/ emitter DHBTs resulted in over 5 W/mm output power at a collector bias of 10 V.<<ETX>>