HIGH-TEMPERATURE MICROWAVE CHARACTERISTICS OF GAAS-MESFET DEVICES WITH ALAS BUFFER LAYERS

AlAs buffers used to reduce the leakage current of high-temperature Ga As MESFET devices are shown to have no detrimental effect on the micro wave performance measured to 200 degrees C. The f(t) values decrease w ith increasing temperature, but do not appear to be influenced by the AlAs buffer. The f(max) values also decrease with increasing temperatu re; however, they are improved with increasing AlAs buffer thickness d ue to a concomitant decrease in the device output conductance. At 200 degrees C ambient temperature, f(t) and f(max) values of 14.5 GHz and 36.7 GHz, respectively, were measured.