The investigation of threshold voltage instability of p-GaN AlGaN/GaN HEMT caused by the measurement

In this paper, the mechanism and law of threshold voltage instability in p-GaN AlGaN/GaN HEMT caused by the tested were investigated. A preprocess and rescan method was used to test the transfer characteristics, and the threshold voltage variation of p-gate schottky contact GaN HEMT was studied under different preprocessing duration, floating time and scanning time of gate pulse voltage. The results show that the threshold voltage instability of p-gate schottky contact GaN HEMT devices is complex and variable under positive voltage preprocessing, and also depends on the downward/upward direction of gate voltage during the scanning of the transfer characteristics. Among them, the charge properties, distribution and flow direction of p-GaN layer are the main reasons for the complexity of threshold voltage variation of p-gate GaN devices.