Bulk breakdown in AlGaN/GaN HFETs

摘要

A significant source current generated by a carrier multiplication process is observed at large drain voltages in the subthreshold regime, along with simulataneous increase of the gate current and light emission signal. Provided no on-surface premature breakdown takes place, a bulk channel avalanche breakdown process is proposed as the dominant breakdown mechanism for a large range of gate-to-source de voltages. This process in the GaN channel is responsible for the excess source and drain currents, light emission, and excess gate current beyond its normal value measured ina gate-to-drain diode configuration. The role of the gate bias in controlling the channel vs.the gate breakdown mechanisms is described.