Reflectance spectroscopy analysis of Si-doped β-Ga₂O₃ films grown by MOVPE: The influence of doping concentration and substrate conductivity

This study examines the feasibility of using in-situ reflectance measurement for Si-doped β-Ga ₂ O ₃ films homoepitaxially grown by metalorganic vapor-phase epitaxy on substrates with varying conductivity (semi-insulating (Mg-doped) and conductive (Si-doped)). Interference oscillation patterns were observed in the wavelength region well below the band gap absorption, with the oscillation amplitudes showing a significant dependence on the doping concentrations of the grown films. Reflectance spectroscopy enables the estimation of growth rate and doping level based on the period and amplitude of the observed Fabry-Pérot oscillations, respectively. These oscillations occur due to the refractive index difference between the grown film and the substrate, which is influenced by doping in the homoepitaxy process and estimated by the Drude model.