Growth Pressure Regulation of Defect-Mediated Transport in Si-Doped β-Ga2O3 Homoepitaxial Films

The electrical properties of Si-doped β-Ga₂O₃ homoepitaxial films are governed by the interaction between Si donor activation and native point defects formed during metal−organic chemical vapor deposition (MOCVD) growth. Although growth pressure directly affects precursor transport, boundary-layer evolution, gas-phase reactions, and surface kinetics, its role in regulating defect-mediated carrier transport remains insufficiently understood. Here, we systematically investigate the effect of the growth pressure on the structural, electrical, and defect properties of MOCVD-grown Si-doped β-Ga₂O₃ (100) homoepitaxial films. The film grown at 40 mbar exhibits a carrier concentration of 4.7 × 10¹⁷ cm⁻³ and a Hall mobility of 120.0 cm²/(V·s). As the growth pressure increases from 50 mbar to 80 mbar, the β-Ga₂O₃ films show a much lower dopant activation efficiency and lower Hall mobility. Combined temperature-dependent Hall, cathodoluminescence, and X-ray photoelectron spectroscopy analyses indicate that elevated pressure reduces the concentration of electrically active Si_Ga(I) donors, which dominates the decrease in carrier concentration, while increasing vacancy-related defects, including gallium-oxygen divacancy (V_Ga-V_O) complexes and oxygen vacancy (V_O)-related oxygen-deficient environments, which act as scattering centers and lower the mobility. Lateral MOSFETs fabricated on the film grown at 40 mbar achieve a drain on/off ratio above 10⁹, a specific on-resistance of 169.8 mΩ·cm², and a breakdown voltage exceeding 3 kV. This work reveals how growth pressure modulates the formation of native defects and defect-mediated carrier transport in Si-doped β-Ga₂O₃ homoepitaxy, providing mechanistic insight into developing high-mobility channel layers for β-Ga₂O₃ power devices.