Wet Etching of β-Ga₂O₃ Substrates

Abstract

Wet etching of (100)-oriented β-Ga2O3 single crystal substrates was carried out using H3PO4 and H2SO4. The etching reactions followed the Arrhenius equation, but the etching in H2SO4 at a high temperature of 190 °C was disturbed by the formation of sulfates on the surface. Considering the higher etching rate over the temperature range of 100–194 °C, H3PO4 is more preferable as an etchant for β-Ga2O3. Although the isotropic etching led to side etching, a grid pattern in the order of µm was successfully fabricated. These results indicate that this simple and low-cost wet etching using H3PO4 is suitable for isolating devices or patterning structures on β-Ga2O3 substrates.