Wet chemical etching behavior of β‐Ga₂O₃ single crystal

Wet chemical etching behavior of β‐Ga 2 O 3 single crystal was investigated to evaluate its chemical stability and to explore etchants for β‐Ga 2 O 3 single crystal. Undoped and Sn‐doped β‐Ga 2 O 3 single crystals were grown by the floating zone method, and (100)‐ and (001)‐oriented samples were chemical‐mechanical‐polished to wafers. The samples were wet chemically etched in solutions such as HCl, H 2 SO 4 , HNO 3 , HF, H 2 O 2 :H 2 SO 4 :H 2 O=1:4:1, KOH, and NaOH. The samples were chemically stable against both acids and alkalis except HF and NaOH. Aqueous HF solution was found to etch β‐Ga 2 O 3 uniformly at room temperature. The etch rate increased with increasing immersion time and HF content. Anisotropy of etch rate was observed between the (100) and (001) planes. The etch rate of Sn‐doped β‐Ga 2 O 3 was lower than that of undoped β‐Ga 2 O 3 , and the etch rate decreased with increasing Sn doping content. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)