Novel GaAs-based devices for microwave and photonic applications above 100 GHz

Recent results related to the two novel GaAs-based devices are described. First one is an InGaAs-InP pseudomorphic HEMT which consists of Al-free material structure. From the analysis results, optimal device performance is demonstrated on an 0.1 /spl mu/m T-gate Al-free InGaAs-InP pHEMT with f/sub T//f/sub max/ of 160/300 GHz. Obtained cutoff frequencies are comparable to the record values reported on InGaAs-InAlAs HEMTs, however Al-free devices show higher breakdown voltages, no kink effects and better reliability. Another novel device is an MSM detector on nonstoichiometric GaAs which is suitable for optical heterodyne mixing up to the THz frequency range. Intrinsic and extrinsic bandwidth of a detector are analysed and a 3-dB bandwidth of 550 GHz, higher than previously reported, is achieved for an optimized device with interdigitated finger contacts. Further possibilities in performance improvement of both types of GaAs-based devices are discussed.