Investigation of Electrical Performance Degradation in p-AlGaN Gate Heterostructure Field-Effect Transistors Under Various Off-Stress Conditions

Abstract

We investigate the effects of various off-state stresses on the electrical performance degradation in p-AlGaN gate heterostructure field-effect transistors (HFETs) which are especially devised for the normally-off operation. The devices were stressed under various off-stress conditions and the transfer curves were measured immediately after stresses. When the negative bias stress was applied only to the gate electrode, the drain current (I-D) decreased and the threshold voltage (V-TH) moved to the positive direction. On the other hand, when the devices were stressed at a fixed negative gate voltage with various positive drain voltages, I-D decreased, but V-TH did not move. These degradations are believed to be the results of electron trapping during the off-state stresses, and the observed different phenomena depending on the off-stress conditions may be attributed to the difference of charge trapping locations.