With ultrawide bandgap (UWBG) semiconductors becoming increasingly popular in recent years as next-generation power electronics materials, scalability toward larger volumes at lower costs is critical to market adoption. Gallium oxide (Ga2O3) is uniquely positioned among UWBGs due to the commercial availability of 100 mm bulk substrates today and the future availability of larger wafer sizes. In addition to scaling wafer sizes, the success of high voltage Ga2O3 devices hinges on the ability to produce thick, low doped epitaxial layers on large area wafers at relatively low costs. Halide vapor phase epitaxy (HVPE) is well suited for rapid growth rates and low impurity films while also reaching large wafer sizes. HVPE has been utilized herein to grow layers thicker than 50 μm with intentional n-type doping 1 × 1016 cm−3 on commercially available 2 in. and 100 mm bulk Ga2O3 (001) wafers. The roughness of as-grown films was reduced through the introduction of H2, with thick layers showing 25 nm roughness over the wafer area. These results further reinforce Ga2O3 as a strong contender for next-generation multi-kV power electronics devices.
Reilly et al. (2026) studied this question.