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, such as phosphoric acid, alkali solutions and molten alkalis, all require operation at elevated temperatures (≥100 °C), which entails additional process complexity and equipment requirements, making them less preferable. 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 °C in an HF–HNO₃ solution for 2 h, and the resulting etch pits exhibited regular morphologies and could be directly distinguished through optical microscopy. This investigation not only expands the scope of etchant selection but achieves defect-selective etching at a reduced temperature of 60 °C, highlighting its commercial potential for the surface treatment of β-Ga₂O₃.