Local Structure of Zn Dopant in β-Phase Ga2O3

Abstract

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 β-phase Ga₂O₃ doped with Zn, which can serve as a suitable acceptor. Thin-film samples with Zn doping concentrations of 1.7 × 10¹⁹ and 2.5 × 10²⁰ ions/cm³ were confirmed as single phases of monoclinic β-Ga₂O₃ by X-ray diffraction. To determine the location of Zn ions within the β-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 β-Ga₂O₃, as well as a precipitation of ZnGa₂O₄ spinel, were compared with the experimental data. The experimental XANES spectra of the Zn L₃ edge were reproduced well by theoretical spectra of Zn ions occupied at cationic positions at the tetrahedral coordinated site.