Device Modeling for Understanding AlGaN/GaN HEMT Gate-Lag

Using a simple simulation framework, it is shown that a passivation dielectric that minimizes surface leakage and creates a high density of shallow traps at the surface is vital to minimize the formation of the virtual gate and eliminate AlGaN/GaN HEMT gate-lag. Under large negative gate voltage, this is also expected to create higher fields and current crowding at the gate edge, promoting an increase in total gate leakage. While the AlGaN barrier properties are also found to impact gate-lag, the use of a passivation dielectric that minimizes surface leakage can overpower it´s influence and suppress current collapse. Access region shrinking and the use of a longer gate are also found to improve gate-lag.