Hot-electron effects on AlGaAs/InGaAs/GaAs PHEMTs under accelerated DC stresses

Abstract

The behavior of Schottky gate characteristics before and after hot-electron stress has been a relatively neglected topic. Thus, this paper discussed the effects of hot-electron accelerated stress on the DC characteristics of AlGaAs/InGaAs/GaAs PHEMTs as they relate to Schottky gate characteristics. It also presents studies of reverse Schottky gate characteristics before and after hot-electron stresses, as related to two major mechanisms: (1) the widening of the depletion region under the gate; and (2) the impact of the carriers trapped under the gate. The former induces a larger Schottky barrier height with a smaller reverse leakage current density than the latter, while the latter induces the opposite. Two hot-electron conditions are used to investigate the impact of the hot-electron stress on the gate leakage current. The gate leakage current decreases after a hot-electron stress, due the effect of hot-electron stress on the Schottky diode characteristics. Moreover, improvement in the noise performance is expected, due to the decrease in the gate leakage current. Both pre- and post-stress noise measurements have been done to demonstrate this.