Degradation mechanism of Ti/Au and Ti/Pd/Au gate metallizations in GaAs MESFET's

Modifications of several dc parameters of GaAs MESFET's induced by accelerated aging at 300 °C have been investigated in a test pattern configuration. Two different gate metallization structures have been examined, namely GaAs/Ti/Au and GaAs/Ti/Pd/Au. The gate diode and the MESFET characteristics of the former degrade noticeably upon annealing, while they are less affected by the thermal treatments for the latter. This different behavior is probably induced by the formation of different compounds at the metal-GaAs interface, which modify the gate diode properties.