S.E. Rosenbaum

Microwave performance of AlInAs-GaInAs HEMTs with 0.2- and 0.1- mu m gate length

The millimeter-wave performance is reported for Al/sub 0.48/In/sub 0.52/As-Ga/sub 0.47/In/sub 0.53/As high-electron-mobility transistors (HEMTs) with 0.2- mu m and 0.1- mu m-long gates on material grown by molecular-beam epitaxy on semi-insulating InP substrates. Devices of 50- mu m width exhibited extrinsic transconductances of 800 and 1080 mS/mm, respectively. External f/sub T/ (maximum frequency of oscillation) of 120 and 135 GHz, respectively, were measured. A maximum f/sub T/ of 170 GHz was obtained from a 0.1*200- mu m/sup 2/ device. A minimum noise figure of 0.8 dB and associated gain of 8.7 dB were obtained from a single-stage amplifier at frequencies near 63 GHz.<<ETX>>

AlInAs-GaInAs HEMTs utilizing low-temperature AlInAs buffers grown by MBE

Low-temperature AlInAs buffer layers incorporated in AlInAs-GaInAs HEMT epitaxial layers grown by MBE are discussed. A growth temperature of 150 degrees C followed by a short anneal is shown to eliminate kinks in the device I-V characteristic and sidegating and to reduce the output conductance dramatically.<<ETX>>

Novel high performance self-aligned 0.15 micron long T-gate AlInAs-GaInAs HEMTs

A novel self-aligned technique for 0.15- mu m-gate-length HEMTs (high electron mobility transistors) has been demonstrated. This technology uses a 0.15- mu m-long T-gate structure defined by e-beam lithography with a SiO/sub 2/ sidewall to implement the self-aligned scheme. The resultant device has low source and drain resistances, low gate resistance (200 Omega /mm), and a passivating layer over the active channel. Devices with an oxide sidewall yielded an f/sub T/ of 177 GHz, whereas devices with no sidewall exhibited an f/sub T/ greater than 250 GHz. The difference has been related to process damage during plasma deposition of SiO/sub 2/.<<ETX>>

A deep-submicrometer microwave/digital CMOS/SOS technology

0.35- mu m complementary metal-oxide-semiconductor (CMOS)/silicon-on-sapphire (SOS) n- and p-channel MOSFETs with a metal-over-polysilicon T-gate structure for monolithic microwave integrated circuit (MMIC) and digital applications are reported. The measured values for the current-gain cutoff frequency f/sub T/ were >or=20 GHz for both n-channel and p-channel devices, and the values for the unilateral power-gain cutoff frequency f/sub max/ were 37 GHz for the p-channel and 53 GHz for the n-channel MOSFETs. The low effective resistance of the T-gate structure contributed to the very high f/sub max/ values. It is believed that these are the highest f/sub T/ and f/sub max/ values ever reported for MOS devices. The potential of SOS submicrometer MOSFETs for microwave circuit applications is demonstrated.<<ETX>>

High performance V-band low noise amplifiers

Significant advances in high-frequency, low noise amplifier (LNA) performance have been achieved. Noise figures under 2.0 dB have been demonstrated with several single-stage amplifiers incorporating devices from different wafers. These amplifiers utilized an Al/sub 0.48/In/sub 0.52/As-Ga/sub 0.47/In/sub 0.53/As lattice matched InP high-electron-mobility transistor device with a gate periphery of 50 mu m*0.2 mu m. The typical f/sub t/ of these devices is in excess of 120 GHz, with an extrinsic g/sub m/ of more than 900 mS/mm. The best result obtained for a single-stage LNA was 0.8 dB, with an associated gain of 8.7 dB at 63.5 GHz. A three-stage V-band amplifier produced a minimum noise figure of 2.6 dB, with 19.5 dB of gain at 61.0 GHz.<<ETX>>

The effect of interface and alloy quality on the DC and RF performance of Ga/sub 0.47/In/sub 0.53/As-Al/sub 0.48/In/sub 0.52/As HEMTs

Ga/sub 0.47/In/sub 0.53/As-Al/sub 0.48/In/sub 0.52/As high-electron-mobility transistors (HEMTs) were fabricated in materials with varying degrees of alloy and interface disorder. The conductivities of the epitaxial layers are highest for material with the smallest amount of interface roughness and lowest for samples with poor-quality interfaces. The transconductances and unity current gain cutoff frequencies of the fabricated devices with 0.2- mu m gates are similarly affected. >

A 2-GHZ three-stage AlInAs-GaInAs-InP HEMT MMIC low-noise amplifier

A three-stage monolithic microwave integrated circuit (MMIC) low-noise amplifier (LNA) has been fabricated using 0.15- mu m-gate-length, InP-based (AlInAs-GaInAs) high electron mobility transistor (HEMT) technology. The LNA exhibited less than 0.5-dB noise figure and greater than 35-dB gain from 2.25 to 2.5 GHz. The input and output return loss exceeded 15 dB across the band. The results are believed to be the best reported to date for a MMIC amplifier in this frequency range.<<ETX>>

AlInAs/GaInAs on InP HEMT low noise MMIC amplifiers

AlInAs/GaInAs on InP HEMT (high electron mobility transistor) single-stage low-noise MMIC (monolithic microwave integrated circuit) amplifiers have been developed for operation at 12 GHz, 35 GHz and 60 GHz. A noise figure of 0.78 dB with an associated gain of 15 dB was achieved at 12 GHz. This is the lowest noise figure yet reported for a monolithic amplifier at 12 GHz. A noise figure of 1.2 dB with gain greater than 12 dB was obtained from 10 to 14 GHz. At 35.5 GHz, 13 dB gain with 17 dB input return loss was obtained. At 55 GHz, 8 dB gain with more than 12 dB input return loss was obtained.<<ETX>>

Low-temperature buffer GaAs MESFET technology for high-speed integrated circuit applications

The fabrication of high-performance digital integrated circuits with low-temperature buffer (LTB) GaAs MESFET technology is presented. Individual 0.2- mu m-gate-length transistors show a g/sub m/ of 600 mS/mm and an extrapolated f/sub T/ of 80 GHz. Backgating and light sensitivity are eliminated with the LTB technology. Static source-coupled FET logic frequency dividers exhibit a maximum clock rate of 22 GHz.<<ETX>>

DC and RF performance of 0.1 mu m gate length Al/sub 0.48/In/sub 0.52/As-Ga/sub 0.38/In/sub 0.62/As pseudomorphic HEMTs

The authors report on the epitaxial layer design, device fabrication, and millimeter-wave performance of lattice-matched and pseudomorphic AlInAs-GaInAs HEMTs (high-electron-mobility transistors). The authors fabricated 0.1- mu m gate length HEMTs using pseudomorphic Al/sub 0.48/In/sub 0.52/As-Ga/sub 0.38/In/sub 0.62/As modulation-doped epitaxial layers and compared them with lattice-matched Al/sub 0.48/In/sub 0.52/As-Ga/sub 0.47/In/sub 0.53/As HEMTs. The pseudomorphic HEMTs demonstrated an external f/sub T/ (current-gain cutoff frequency) of 205 GHz, which is the first demonstration of a transistor with an f/sub T/>200 GHz. The V-band noise figure of an amplifier built with the lattice-matched HEMT and the pseudomorphic HEMTs was 1.3 dB and 1.5 dB, respectively. The associated gain was 9.5 dB and 8.0 dB, respectively.<<ETX>>