Samsung Advanced Institute of Technology

This work reports the transient measurement of the AlGaN/GaN high electron-mobility transistor (HEMT) drift region potential in the high power state during switching. Transient measurement during high power stress is challenging, since AlGaN/GaN HEMTs can sustain high power stress only for a few ms before failure occurs. The effect of high power stress has been reported only by device characterization after stress or during high power DC stress at voltages below the operating voltages. In this work, a test structure with voltage probes inserted in the drift region between the gate and the drain is used to perform real-time measurement of the drift region potential during the high power state at operating voltages. It is found that the high electric field formed at the gate side during the off-state stress propagates towards the drain side within a few ms. The propagation speed of this high electric field increases with increase in drain voltage. It is proposed that trapping of hot channel electrons is causing this effect, and dynamic on-resistance measurement suggests that the traps are 0.44 eV below the conduction band.