Demonstration of MOCVD based in situ etching of β-Ga₂O₃ using TEGa

In this work, we demonstrate an in situ etch technique for β-Ga₂O₃ inside a metalorganic chemical vapor deposition (MOCVD) reactor using triethylgallium (TEGa) as the etching agent. At sufficiently high substrate temperatures (T_sub), TEGa is introduced into the MOCVD reactor which undergoes pyrolysis, resulting in the deposition of Ga on the β-Ga₂O₃ surface. These Ga adatoms react with Ga₂O₃ to form gallium suboxide (Ga₂O), which desorbs from the β-Ga₂O₃ surface resulting in the etching of the epilayer. MOCVD chamber parameters such as TEGa molar flow rate, substrate temperature, and chamber pressure were shown to be key in controlling the etch rate and surface morphology. A wide range of etch rates from ∼0.3 to 8.5 μm/h is demonstrated by varying the etch parameters. In addition, smooth surface morphology on (010) and (001) β-Ga₂O₃ substrates is also demonstrated. This new etch technique could enable damage free fabrication of 3D structures like fins and trenches, which are key components in many β-Ga₂O₃ device structures.