Optical properties of oxygen vacancy in gamma-LiAlO2: A computational study

Abstract

• Alkauskas’ method is employed to relieve the band edge problem. • The defect formation energy is aligned with the finite-size correction (FNV). • The point defect Vo 2+ is relative stable in most situations. • The electron-phonon coupling during the optical transition process is calculated. • F center and F + center play an indispensable role in luminescence and absorption. To obtain more accurate optical properties, we optimize the oxygen vacancy in gamma-LiAlO 2 with three different charges (0, +1, +2) to study the optical spectrum line shapes of the oxygen vacancy, and the defect formation energies are corrected by finite-size correction scheme (FNV). We obtain the optical spectra containing electron-phonon coupling. The absorption spectra of the F center and F + center peak at 4.6 eV and 5.5 eV, which are close to the experimental result. So we predicate that the absorption band peak at 5.21 eV should be the origin of the F + center. The luminescence peaks of the F center and F + center are at 2.98 eV and 2.56 eV, respectively. Comparing with the experimental results, the emission peak (3.02 eV) is caused by the F center.