Influence of self-heating on the impact-ionization gate leakage in AlInAs/InGaAs/InP HEMTs

Excess gate leakage in AlInAs/InGaAs/InP HEMTs, resulting in a hump-shape superimposed to the conventional reverse current characteristics has been documented as originating from holes created by impact ionization in the channel. In some instances an anomalous behaviour has been reported with the appearance of double-hump Ig (Vgs) characteristics: while a first gate current hump appears close to pinch-off, a second hump shows up in open channel conditions, at higher drain voltages. In this paper, we show this feature of the gate leakage can be ascribed to the device self-heating, and the open-channel hump can be used to monitor the channel temperature.