10. Halide Vapor Phase Epitaxy 1

Homoepitaxial growth of β-Ga₂O₃ on β-Ga₂O₃ substrates by halide vapor-phase epitaxy (HVPE) using GaCl and O₂ was investigated by both thermodynamic analysis and growth experiments. The thermodynamic analysis clarified that growth of Ga₂O₃ is expected at high temperatures around 1000 °C using an inert carrier gas. The experimental results revealed that homoepitaxial growth of unintentionally doped (UID) layers with a low effective donor concentration (N_d − N_a) of less than 10¹³ cm⁻³ is possible at 1000 °C on β-Ga₂O₃ (001) substrates with a high growth rate of up to 28 μm/h. Furthermore, HVPE growth of intentionally Si-doped β-Ga₂O₃ layers was investigated by supplying SiCl₄, which revealed that n-type carrier density almost equal to the Si-doping concentration can be controlled in the range of 10¹⁵–10¹⁸ cm⁻³. The carrier mobility decreased with increasing Si impurity concentration and was about 150 cm²/V·s at room temperature for a layer with a carrier density of 3.2 × 10¹⁵ cm⁻³. Thus, the intentionally Si-doped homoepitaxial layers grown on β-Ga₂O₃ substrates can be applicable for the production of β-Ga₂O₃-based power devices.