First-principles insight into electrical characteristics of rhodium in vertical Bridgman-grown β-Ga2O3 with experimental validation

The vertical Bridgman (VB) method is a promising approach for growing high-quality, large-sized β-Ga2O3 single crystals. However, rhodium (Rh) from the Pt–Rh alloy crucible can diffuse substantially into the melt during crystal growth, leading to unintentional doping of the crystal. Herein, first-principles calculations were performed to investigate the incorporation behavior and electronic effects of Rh impurities in β-Ga2O3. It was revealed that Rh preferentially occupies the octahedral Ga sites, exerting minimal influence on n-type or semi-insulating β-Ga2O3 but acting as a deep-level donor that may inhibit p-type conductivity. Experimental growth of both Fe- and Sn-doped 4-in. β-Ga2O3 crystals by the VB method yielded electrical conductivities comparable to crystals grown by other approaches, thereby validating the predicted electrical properties of Rh. Our study elucidates the electrical characteristics of Rh in β-Ga2O3 theoretically and experimentally, providing guidance for optimizing VB growth processes and advancing the fabrication of high-performance β-Ga2O3-based electronic devices.