Characterization of Dynamic Threshold Voltage in Schottky-Type p-GaN Gate HEMT Under High-Frequency Switching

The dynamics of the intrinsic threshold voltage ( VTH) shift in 650-V Schottky-type p-GaN gate HEMT under high-frequency switching is investigated by a bootstrap voltage clamping circuit in which the GaN HEMT serves as the key bootstrapping device. This new testing setup covers a wide range of OFF-state drain bias ( VDSQ) up to 400V, a short OFF-to-ON (or stress-to-sense) delay ( Tdelay) of 60ns, and a high switching frequency ( fsw) up to 2MHz. The dynamic VTH's dependences on VDSQand fsware characterized by this testing setup. A higher VDSQ(up to 400V) results in a larger dynamic VTHshift (VTH). The △VTHexhibits a gradually increasing trend under the continuous high-frequency switching mode. In addition, after continuous switching operation for 200μs, the maximum △VTHshows no fswdependence with a wide range of frequency from 50kHz to 2MHz.