Self-aligned T-shaped Au/WSiN gate i-InGaP/n-InGaAs/i-GaAs heterostructure MESFETs with a BP-LDD structure were developed for application to microwave and millimeter-wave communication systems. Owing to the use of tilted-angle n+-ion-implantation, symmetric and asymmetric structures FETs can be fabricated on the same chip and low noise, high breakdown voltage, and high power gain can be attained simultaneously. The fabricated symmetric FETs, with a gate length of 0. 13 µm, exhibit a current cutoff frequency of more than 70 GHz and a minimum noise figure as low as 1. 0 dB at 20 GHz, while the gate-drain breakdown voltage is more than 8 V and the MSG is as high as 7. 8 dB at 60 GHz in the asymmetric FETs on the same chip. V-band MMIC amplifiers fabricated using symmetric FETs exhibit a gain of more than 9 dB and a noise figure of 6 dB over the 50 to 60 GHz frequency range.

This paper describes small AlGaAs/GaAs HBT's for low-power and high-speed integrated circuits. The device fabrication is based on a new bridged base electrode technology that permits emitter width to be defined down to 1 µm. The new technology features oxygen-ion implantation for emitter-base junction isolation and zinc diffusion for extrinsic base formation. The oxygen-ion implanted emitter-base junction edge has been shown to provide a periphery recombination current much lower than that for the previous proton implanted edgs, the result being a much higher current gain particularly in small devices. The zinc diffusion offers high device yield and good uniformity in device characteristics even for a very thin (0.04 µm) base structure. An HBT with emitter dimensions of 12.4 µm2 yields an fT of 103 GHz and an fmax of 62 GHz, demonstrating that the new technology has a significant advantage in reducing the parasitic elements of small devices. Fabricated one-by-eight static frequency dividers and one-by-four/one-by-five two-modulus prescalers operate at frequencies over 10 GHz. The emitters of HBT's used in the divider are 12.4 µm2 in size, which is the smallest ever reported for AlGaAs/GaAs HBT IC's. These results indicate that the bridged base electrode technology is promising for developing a variety of high-speed HBT IC's.