Electro-thermal reliability analysis and performance evaluation of a 1.2 kV cascode GaN HEMT for high-power-density applications

Abstract This work presents a comprehensive electro-thermal and reliability characterization of a 1.2 kV GaN high-electron-mobility transistor (HEMT) in a cascode configuration, systematically evaluating its potential for high-power applications. This study reveals key parametric temperature dependencies: a threshold voltage temperature coefficient of −1.16 mV °C ⁻¹ , ensuring stable gate switching across a wide temperature range, and a distinct positive temperature coefficient of on-state resistance, which provides inherent current-sharing capability in parallel operation and mitigates thermal runaway risks. Dynamic analysis demonstrates nanosecond-scale switching speeds (rise time: t _r = 14 ns; fall time: t _f = 12 ns), low gate charge (10.5 nC), and low output charge (71 nC), indicating strong suitability for high-frequency zero-voltage-switching converters. Reliability assessment confirms excellent gate oxide integrity, evidenced by pA level gate leakage current, and defines safe operating boundaries under both transient and steady-state conditions through safety operating area analysis. These results not only provide a complete characterization profile of the high-voltage GaN HEMT but also offer physical insights into its operational mechanisms, supplying critical data and theoretical guidance for future application-oriented design and optimization.