BIAS-DEPENDENT COLLAPSE AND ITS RECOVERY PHENOMENON IN ALGAAS/GAAS 2DEGFETS AT LOW-TEMPERATURES

Current-voltage characteristics for AlGaAs/GaAs 2DEGFET's have been investigated at low temperatures in terms of stress biases and stress time. The study reveals that the degree of collapse strongly depends on the magnitude of the stress drain voltage. The device exhibits seriously collapsed I-V characteristics when the stress drain voltage is chosen at around 1.2 V. Application of higher stress drain voltages leads to less distorted I-V characteristics, demonstrating a new collapse-recovery mechanism without the need for illuminating or heating the device, and therefore the heavily collapsed state and the recovered state can be switched with each other by simply changing the value of the stress drain voltage. Based on the gate current analysis during the bias stress step, we attribute the mechanism responsible for the drain-stress-induced recovery phenomenon to the ionization of DX centers by capture of holes generated by impact ionization.