Ultrathin-Body GaN-on-Sapphire HEMT with Megahertz Switching Capability Under Prompt Irradiation Dose Rate Exceeding 10¹⁰ rad(Si)/s

This work demonstrates ultrathin-body GaN HEMTs on 6-inch sapphire substrate with robust irradiation hardness against prompt dose rate (PDR) and single-event effect (SEE). By implementing low-temperature physical vapor deposition and high-temperature metalorganic chemical vapor deposition growth technologies, the GaN channel layer is directly grown on the AlN/Sapphire to form a thin epitaxy (i.e., GaN buffer is omitted). As a result, the irradiation-induced collection charge, which is highly dependent on the body thickness, is significantly reduced from 2.07 μC to 5.13 pC under 4.2 × 10 ¹⁰ rad(Si)/s PDR irradiation. The resulting device achieves megahertz switching capability, setting a new irradiation performance record for power devices. Furthermore, by performing ultraviolet pulsed laser SEE technology, the device exhibits a minimal collection charge of 0.21 pC under linear energy transfer (LET) condition of 77.6 MeV·cm ² /mg. In particular, the SEE burnout voltage of the device is enhanced to 638 V, which is the highest value reported in GaN devices to date. These results show the great promise of the ultrathin-body GaN-on-sapphire HEMTs for irradiation applications.