Photoelectron Holographic Study for Atomic Site Occupancy for Si Dopants in Si-Doped -Ga₂O₃(001)

We investigated atomic site occupancy for the Si dopant in Si-doped kappa-Ga2O3(001) using photoelectron spectroscopy (PES) and photoelectron holography (PEH). From PES and PEH, we found that the Si dopant had one chemical state, and three types of inequivalent Si substitutional sites (Si-Ga) were formed. The ratios for the inequivalent tetrahedral, pentahedral, and octahedral Si-Ga sites were estimated to be 55.0%, 28.1%, and 16.9%, respectively. Higher (lower) ratios for the three inequivalent Si-Ga sites may come from a lower (higher) formation energy. The Tetra (Octa) Si-Ga site has the highest (lowest) ratio of the three Si-Ga sites since it has the lowest (highest) formation energy. We suggest that the tetrahedral Si-Ga site is due to the active dopant site, whereas the pentahedral and octahedral Si-Ga sites can be attributed to the inactive dopant sites for Si-doped kappa-Ga2O3(001).