Mechanism analysis and protection design of GaN HEMTs induced by high-power microwave pulse

This study investigates the damage mechanisms induced by HPM stress in GaN HEMTs using Sentaurus TCAD numerical simulations and proposes corresponding multi-scale protection strategies. A comprehensive simulation model of a depletion-mode GaN HEMT was established. The analysis of the evolution of internal electric field, current density, and temperature profiles under HPM stress reveals that the failure mechanism is primarily attributed to an electro-thermal positive feedback loop between the gate and source, leading to thermal accumulation and eventual thermal breakdown when the lattice temperature reaches the melting point of GaN. Based on this understanding, protection strategies were developed through structural optimization. The results demonstrate that moderately increasing the gate length (0.25-0.3<i>μ</i>m), extending the field plate length (1.85-2.25<i>μ</i>m), and optimizing the channel layer thickness (0.4-0.6<i>μ</i>m) effectively reduce the internal electric field and current density, thereby mitigating thermal accumulation and enhancing HPM resilience without significantly compromising DC performance.