Dynamic Overvoltage and Energy Loss in p-GaN HEMTs Under Ultraviolet Pulsed Laser-Induced Single Event Irradiation

The robustness of non-avalanche p-GaN gate HEMTs against dynamic overvoltage $(V_{\mathbf{o}\mathbf{v}\mathbf{e}\mathbf{r}}.)$ and transient surge-energy shocks is critical for device applications, especially for extreme irradiation switching applications. By employing ultraviolet (UV) pulsed laser irradiation experimental techniques, this work evaluates the unclamped inductive switching (UIS) robustness of p-GaN HEMTs under single-event irradiation for the first time. It is found that the critical $V_{\mathbf{o}\mathbf{v}\mathbf{e}\mathbf{r}}$. of the device decreases from 1109 V to 897 V, corresponding to a degradation rate of 19%. While the UIS-dominated surge energy loss $(E_{\mathbf{l}\mathbf{o}\mathbf{s}\mathbf{s}})$ is reduced. Under single-event irradiation, a large amount of charge will be generated within the device body along the incident track. As a result, the acceptor-like traps in the buffer layer are pre-filled with irradiation-induced electron charges. The resulting intensified electric field on the drain-side deteriorates overvoltage capability, whereas the charge imbalance between the UIS charging and discharging phases is alleviated, as confirmed by circuit modeling and TCAD simulations. These findings on UIS characteristics provide critical insights for device applications in irradiation environments.