First-principles investigation of structural modification, fine band gap engineering, and optical response of La1-xBaxGaO3for optoelectronic applications

Oxide-based perovskites offer intriguing applications in multiple innovative areas due to their structural and physical properties such as photoluminescence, colossal magneto-resistivity, ferroelectricity, superior piezoelectric, optical, and electronic properties. Lanthanum gallate -(LaGaO3) is a promising perovskite material for microwave application and as a substrate material for super conductors. Here, we aim to explore the relationship between the structural distortion induced in LaGaO3 octahedra as a function of Barium (Ba) doping concentration (x = 0, 0.03, 0.18, 0.33, 0.37, 0.59, 0.74, 0.96, 1), and its structural, electronic and optical properties. The computed band gap for pure c-LaGaO3 is 2.91 eV, which is in direct in nature, and transforms into direct band gap after Ba doping. In addition, it is observed that the band gap of c-LaGaO3 varies from 2.91 to 2.03 eV, as a function of Ba-doping concentration. The structural properties of c-LaGaO3 are observed to vary significantly w.r.t different Barium concentrations, inserting comprehensive changes in its electronic and optical properties. The static dielectric function epsilon(1)(0)), a measure of the polarizability of the material, significantly enhances for Ba-doped system LaGaO3 from 32 to 215.5. Higher static refractive index (n(0)) is also evident after Ba-doping, which explains the increasing transparency as a function of Ba doping. Hence we suggest Ba-doped LaGaO3 as a good material for optoelectronic applications.