熱力学解析と成長実験によるβ-Ga₂O₃薄膜のMOVPE成長の検討

抄録

  The growth of β-Ga₂O₃ films by metalorganic vapor phase epitaxy (MOVPE) has been investigated by thermodynamic analysis and growth experiments. Triethylgallium (TEGa) and oxygen (O₂) were selected as the source gases, and the inert gas was selected as the carrier gas. Thermodynamic analysis revealed that O₂ is consumed in the combustion of TEGa-derived hydrogen and hydrocarbons, and as a result, a high input VI/III ratio is essential for the growth of β-Ga₂O₃. Based on the thermodynamic analysis, a smooth β-Ga₂O₃ film oriented to (201) and showing an optical bandgap of 4.84 eV was successfully grown at 900℃ at about 1.4 μm/h on a c-plane sapphire substrate. By growing at higher temperatures, the concentrations of hydrogen and carbon impurities in the grown films became lower than the background levels of the measurement system. These results indicate that the MOVPE is promising as one of the growth methods for β-Ga₂O₃.