Generalized thermal rectifier model with optimal thermal rectification ratio and its application to Ga₂O₃-based...

Thermal rectification, arising from asymmetric heat transport under opposite temperature gradients, is essential for thermal management in electronics. We present a generalized optimization strategy for two-segment rectifiers based on Fourier's law, showing that the rectification ratioR, defined as the forward-to-reverse heat flux ratio, is maximized when the interface temperatures coincide in both directions. By expressingRas a function of interface temperature and extending the analysis to arbitrary temperature-dependent thermal conductivitiesκ(T), we develop an analytical framework to optimize rectifiers with dissimilar segments. We demonstrate that higher nonlinearity in the thermal conductivity of the paired material enhances the optimized rectification ratio. The framework is applied to wide-bandgap gallium oxide heterojunctions, where we evaluate maximum rectification ratios for both idealized and real materials. Device-level simulations using the finite-difference time-domain method in energy2D confirm the theoretical predictions.