Bandgap Engineering in Yttrium–Aluminum Garnet with Ga Doping

We report the results of the investigation of Ga-doping effects on the electronic structure of the yttrium–aluminum garnet. The bandgap structure was studied both experimentally using thermally stimulated luminescence technique and theoretically by first-principles density functional theory calculations. We observe a nonlinear decrease in the conduction band minimum with respect to the vacuum referred binding energy with an increase in Ga doping and argue that the effect can be explained by taking into account different influences of the distorted crystal field on the molecular orbitals of the crystal unit cell. The reported nonlinear behavior is important for the band engineering of scintillators based on multicomponent garnets.