Local Structure of Zn Dopant in β-Phase Ga2O3

Ga2O3 is a promising ultrawide-bandgap semiconductor for high-voltage and high-power applications, yet achieving reliable p-type electrical conductivity remains a significant challenge. We utilized halide vapor phase epitaxy growth to synthesize epitaxial layers of beta-phase Ga2O3 doped with Zn, which can serve as a suitable acceptor. Thin-film samples with Zn doping concentrations of 1.7 x 1019 and 2.5 x 1020 ions/cm3 were confirmed as single phases of monoclinic beta-Ga2O3 by X-ray diffraction. To determine the location of Zn ions within the beta-Ga2O3 lattice, we employed X-ray absorption near-edge structure (XANES) in conjunction with first-principles density functional theory calculations. Theoretical XANES spectra for Zn substitutions in the tetrahedral and octahedral Ga sites in beta-Ga2O3, as well as a precipitation of ZnGa2O4 spinel, were compared with the experimental data. The experimental XANES spectra of the Zn L 3 edge were reproduced well by theoretical spectra of Zn ions occupied at cationic positions at the tetrahedral coordinated site.