First-principles investigation of structural modification, fine band gap engineering, and optical response of La1−xBaxGaO3 for 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 ε10\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \left( {\varepsilon_{1} \left( 0 \right)} \right) $$\end{document}, a measure of the polarizability of the material, significantly enhances for Ba-doped system LaGaO3 from 32 to 215.5. Higher static refractive index n0\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \left( {n\left( 0 \right)} \right) $$\end{document} 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.