Abstract
In this study, the optimized hybrid functional HSE(0.26,0.0) is employed to investigate the incorporation of nickel (Ni) and iridium (Ir) dopants in β-Ga(2)O(3). The formation energies and charge transition levels of Ni and Ir at gallium sites are calculated. The results show that Ni prefers substitution at the octahedral (Ga(2)) site, with a formation energy approximately 1 eV lower than at the tetrahedral (Ga(1)) site. Ni at the Ga(2) site (Ni(Ga(2)) ) exhibits both donor and acceptor behaviors, with charge transition levels at (+1/0) 1.0 eV and (0/-1) 2.24 eV above the VBM, respectively. Ir similarly favors the octahedral site, displaying donor behaviors with charge transition levels at (+2/+1) 1.04 eV and (+1/0) 3.15 eV above the VBM. Our computational findings for the charge transition levels of Ni and Ir ions are in good agreement with recent experimental measurements, and they explain the correlation between Ni(3+) and Ir(4+) ion concentrations observed in electron paramagnetic resonance studies. Additionally, the calculated vertical transitions at 2.56 eV and 4.25 eV for Ni(Ga(2)) , and at 2.91 eV and 4.62 eV for Ir(Ga(2)) , below the conduction band minimum, are in good agreement with optical absorption results, confirming the presence of Ni and Ir substitutions at the Ga(2) site in β-Ga(2)O(3). These computational results provide a detailed understanding of the behavior of Ni- and Ir-doped β-Ga(2)O(3), highlighting the potential applications of Ni- and Ir-doped β-Ga(2)O(3) for optoelectronic devices.