Material Properties of n-Type β-Ga₂O₃ Epilayers with In Situ Doping Grown on Sapphire by Metalorganic Chemical Vapor Deposition

In this study, in situ, Si-doped heteroepitaxial Ga₂O₃ layers are grown on c-plane sapphire by metalorganic chemical vapor deposition. The X-ray diffraction peaks of the doped Ga₂O₃ epilayers shows ß-phase of Ga₂O₃, and full width at half maximum of Ga₂O₃ crystallinity is decreased at a Tetraethoxysilane (TEOS) molar flow rate of 2.23 × 10⁻⁷ mol min⁻¹ but increased with higher flow rates. The dopant concentrations of Ga₂O₃ grown at 825 °C with TEOS molar flows of 2.23 × 10⁻⁷, 4.47 × 10⁻⁷, and 6.69 × 10⁻⁷ mol min⁻¹ are measured to be 5.5 × 10¹⁹, 1.1 × 10²⁰, and 1.4 × 10²⁰ atom cm⁻³, respectively, using secondary ion mass spectra and Hall measurements reveal n-type nature with carrier concentrations of 6.5 × 10¹⁷, 3.2 × 10¹⁸, and 3.9 × 10¹⁸ atom/cm³, respectively. To increase Si dopant activation, Ga₂O₃ growth temperature is raised to 875 °C. The result suggests a higher growth temperature can contribute to a greater probability of Si substitution on Ga lattice sites, which further reduces the resistivity of Ga₂O₃ epilayer. Moreover, results are compared with theoretical Density Functional Theory studies.