Thermal stability of GaAs MESFETs fabricated using only spin-on metal sources

GaAs MESFETs were fabricated using spin-on platinum as the gate material and spin-on tin-silica as the source and drain material. They were subsequently aged at elevated temperatures (200, 300, and 400°C) for durations up to 1000 h. DC electrical characterisation of the MESFETs was carried out during various stages of annealing. The results show that the MESFETs fabricated using spin-on metal sources have acceptable electrical characteristics. The progressive degradation in the electrical parameters of the MESFET is described in terms of the degradation of the ohmic and the Schottky contacts. The room temperature (300 K) operating life of GaAs MESFETs, based on a failure criterion of a 20% decrease in the transconductance g_m, is found to be 10 ⁶ h