High-temperature microwave characteristics of GaAs MESFET devices with AlAs buffer layers

AlAs buffers used to reduce the leakage current of high-temperature GaAs MESFET devices are shown to have no detrimental effect on the microwave performance measured to 200/spl deg/C. The f/sub t/ values decrease with increasing temperature, but do not appear to be influenced by the AlAs buffer. The f/sub max/ values also decrease with increasing temperature; however, they are improved with increasing AlAs buffer thickness due to a concomitant decrease in the device output conductance, At 200/spl deg/C ambient temperature, f/sub t/ and f/sub max/ values of 14.5 GHz and 36.7 GHz, respectively, were measured.