First-principles investigation of Zn-doped β-Ga2O3: Electronic, optoelectronic, and thermodynamic properties

Abstract

Monoclinic β-Ga₂O₃ is a promising ultrawide-bandgap semiconductor (4.9 eV) for power electronics and deep-ultraviolet optoelectronics; however, p-type doping still remains a formidable challenge. Using first-principles GGA + U calculations, we examine the site preference, structural stability, and the evolution of electronic, optical, and thermodynamic properties in Zn-doped Ga₂O₃. Zn preferentially substitutes tetrahedral Ga(1) with the lowest formation energy (5.03 eV) and induces negligible (<1 %) lattice distortion, confirmed by phonon dispersion. Zn substitution narrows the bandgap from 5.17 eV to 4.98 eV and yields complete spin polarization at the conduction band minimum, driven by O-2p、Zn-3d、Ga-4s hybridization. Differential charge density and bond-population analyses reveal weakened Ga-O covalency and enhanced ionic character upon doping. Optically, Zn incorporation redshifts the main absorption peaks and lowers the dielectric-response intensity. Thermodynamic calculations show reduced Gibbs free energy and sustained high heat capacity (∼10R at 300 K), indicating improved thermal stability.