Vertical β-Ga2O3 Schottky barrier diodes with low surface roughness

We investigate the properties of the β-Ga2O3 Schottky barrier diodes (SBDs) fabricated on halide vapor phase epitaxy-grown (001)-oriented β-Ga2O3 epilayers with various surface treatment techniques. The surface etching methods employed include two-step inductively coupled plasma (ICP) etching, wet etching, and two-step dry etching followed by wet etching. Combining atomic force microscopy and x-ray photoelectron spectroscopy, we found that the surface roughness and oxygen vacancies (VO) in the epilayers were significantly reduced by employing a two-step ICP etching followed by wet etching. The optimized surface exhibits a root-mean-square roughness of 0.12 nm and a step-flow morphology. The SBDs fabricated on the optimized epilayers achieve a comprehensively enhanced performance, with a breakdown voltage of 1675 V, a near-ideal ideality factor of 1.05, and a power figure of merit of 467 MW/cm2.