A Novel Defect-Selective Etching Method for β-Ga₂O₃ Single Crystals Based on Hydrofluoric Acid

Abstract

Wet chemical etching is widely applied in wide-bandgap semiconductors such as β-Ga₂O₃ due to its high efficiency, simplicity, and low cost. It can reveal surface defects via differential etching rates (defect regions manifest as etch pits), with the choice of etchant being critical. Conventional etchants, like phosphoric acid, alkali solutions and molten alkali, all require operation at elevated temperatures (≥100 ℃), potentially leading to side reactions and compromise operational safety. In this work, we investigated the defect-selective etching of β-Ga₂O₃ (100) surfaces using a mixed HF-HNO₃ solution at lower temperatures. Dislocations and voids were effectively revealed after immersing at 60 ℃ HF-HNO₃ solution for 2 h, the resulting etch pits exhibit regular morphologies and direct differentiation through optical microscopic. This investigation not only expands the scope of etchant selection but achieves defect selective etching at a reduced temperature of 60 ℃, highlighting its commercial potential for surface treatment of β-Ga₂O₃.