Parasitic channel induced by an on-state stress in AlInN/GaN HEMTs

Abstract
In this paper, we have highlighted that an on-state stress can induce a parasitic channel in AlInN/GaN HEMTs. The devices have been stressed during 216 h with a drain-to-source voltage (VDS) of 20 V and a gate-to-source voltage (VGS) of 0 V. A decrease in the drain current (IDS max) of 43%, an increase in the access resistance (RON) of 100%, and a drop in the maximum extrinsic transconductance (gm max) from 234 mS/mm down to 144 mS/mm have been observed after the ageing test. Moreover, a double peak feature is shown in the gm (VGS) characteristic 4 months after the end of the on-state stress. Consequently, we can conclude that a parasitic channel has been created by the on-state stress in the AlInN/GaN transistors. At the same time, no degradation of the Schottky contact has been highlighted after the ageing test.