Modeling rare earth metal alloying in wide band gap oxides

Substitutional Gd alloying (Gd_Ga) in β-Ga₂O₃ is studied using hybrid density functional theory. Structural properties show a monotonic increase in lattice parameters, volume and interplanar spacing with increasing Gd content implying the lattice expands to stabilize the larger atom. Cohesive energy and formation energy calculations show monotonically decreasing energy for increased Gd concentrations, implying stability even for large concentration Gd alloying. Optoelectronic properties for Gd content up to 37.5% show a noticeable red shift across all properties, which reveals how Gd alloying may be used to tune Ga₂O₃-based devices without significantly modifying the atoms which contribute to photoexcitation/emission (band edges); this includes radiation detection applications where high chemical stability, and a large nuclear cross section are required.