Research on the Thermal Failure Mechanisms of Ga₂O₃ Power Devices

The ultra-wide bandgap semiconductor β-Ga₂O₃ attracts extensive attention for next-generation ultra-high-voltage power devices due to its extremely high breakdown field strength (theoretical value of up to 8 MV/cm) and excellent Baliga's figure of merit (BFOM up to 5120). However, its intrinsic thermal conductivity is extremely low (only 10-30 W/m·K at room temperature, with significant anisotropy), which is less than one-tenth that of silicon carbide, poses a major bottleneck limiting high power density applications. In high-power operation, the obvious self-heating phenomenon will cause the junction temperature of the device to rise significantly, further resulting in a series of conditions such as reduced carrier mobility, threshold voltage drift, and reliability degradation. In search of solutions, current studies focus on multi-faceted thermal management schemes from materials, device structures to packaging processes. This article aims to systematically compare and review these solutions. At material level, technical pathway of heterogeneously integrated high thermal conductivity substrate (e.g., SiC or diamond) was discussed, in which Van der Waals heterogeneous integration technology is expected to reduce interface thermal resistance to extremely low levels. At device level, the optimization effect of electrical designs such as double drift layer and lateral graded doping on the distribution of electric fields and heat generation was analyzed. At system level, heat dissipation efficiency of advanced packaging technology, such as substrate thinning and mesa termination was estimated. Through the multidimensional comparative research, this work aims to provide a theoretical basis and technical roadmap for developing high-performance, highly reliable β-Ga₂O₃ power devices.