Tuning the essential physical properties of thermodynamically stable LaAlO3 perovskite: A first principles quantum analysis for the developments in optoelectronic devices

Abstract

The structural, electronic, optical, elastic, mechanical and thermoelectric properties of cubic LaAlO₃ are studied under different pressure ranges (0–100 GPa) using first-principles calculations. The calculations are done using the Generalized Gradient approximation-Perdew-Burke-Ernzerhof (GGA-PBE) by utilizing the CASTEP code. The presence of positive phonon affirms the dynamical stability of cubic LaAlO₃ compound under applied pressures. It was noticed that with the increase of applied pressure, the band gap increased and the nature of the band gap changed from being indirect to direct at 60 GPa. The optical aspects of cubic LaAlO₃ have been thoroughly studied via the use of different optical parameters like the complex refractive index, complex dielectric function, absorption coefficient, energy loss function, real optical conductivity and reflectivity. These investigations cover a broad energy range from 0-50 eV. The photon absorption initiates in the visible region, with the highest level of absorption occurring inside the UV energy range. Our study indicates that LaAlO₃ sustains its cubic phase and has superb mechanical stability, demonstrating its brittle nature under applied pressure between 0 and 100 GPa. The positive values of the Hall coefficient confirm that the holes are the predominant carriers under all externally given pressures from 0 to 100 GPa. As a result, the cubic LaAlO₃ perovskite oxide exhibits suitability for energy-efficient white-LED devices and different optoelectronic applications across various applied pressures.