Physical Insight Into Temperature‐Dependent Power Limits in GaN and 4H‐SiC: A Comparative Study of Baliga's Figure of Merit and R on,sp –  V br Tradeoffs

The unipolar power‐performance metric, Baliga's figure of merit (BFOM), is routinely quoted at room temperature, neglecting the fact that both low‐field mobility ( μ ) and critical electric field ( E cr ) exhibit strong, material‐specific temperature and doping dependencies. This work presents a comprehensive, calibrated theoretical framework to quantitatively evaluate the unipolar R on,sp − V br limits and BFOM of GaN and 4H‐SiC over a wide range of drift‐doping ( N D = 5 × 10 15 to 5 × 10 17 cm −3 ) and temperatures ( T = 300–450 K). By integrating temperature‐dependent impact‐ionization models with mobility models considering various scattering mechanisms, we provide physical insights into the diminishing performance advantage of GaN over 4H‐SiC at elevated temperatures. A sensitivity analysis on GaN's E cr parameters further confirms the robustness of our comparative results. Our findings reveal that the power‐handling capability of GaN remains superior, yet its relative merit compared to 4H‐SiC scales significantly with operational conditions due to differing rates of E cr enhancement and μ degradation. These results offer critical design guidelines for predicting the performance boundaries of next‐generation wide‐bandgap power devices in realistic high‐temperature environments.