Gaas Mixer Diode Burnout Mechanisms at 36-94 GHz

GaAs Schottky barrier diodes fabricated with different high temperature barrier metals were investigated for CW and pulse burnout. The (TiW-Au)-GaAs, (Ti-Mo-Au)-GaAs, and Pd-GaAs diodes, optimized for 36-94 GHz operation were studied in a multi-junction configuation. The burnout mechanism was characterized by a gradual degradation in noise figure. The physical mechanism consisted of a degradation of metal-GaAs interface by the creation of Ga vacancles in the epitaxial layer and a decrease in GaAs mobility. Pulse burnout at X-band consisted of rapid metal punchthrough and catastrophic failure but with a gradual degradation in noise figure. An optimum CW burnout level of 2.0-2.5 watts was obtained with a thermal compression bonded (TiW-Au)-GaAs mixer diode at 36 GHz.