First-principles calculations to investigate ultra-wide bandgap semiconductor behavior of NaMgF3 fluoro-perovskite with external static isotropic pressure and its impact on optical properties

Abstract

The structural, electronic, and optical properties of cubic fluoro-perovskite NaMgF3 were investigated theoretically at pressures ranging from 0 to 100 GPa with a 10-step escalation, i.e., 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100 GPa. The research is conducted by using density functional theory (DFT) based CASTEP (Cambridge Serial Total Energy Package) code with ultra-soft pseudo-potential USP plane wave and Perdew Burke Ernzerhof (PBE) exchange-correlation functional of Generalized Gradient Approximation (GGA). The band gap is found to be increasing from 5.749 to 8.723 eV when the pressure is increased from 0 to 100 GPa. The nature of the band gap remained indirect whether the pressure was applied or not. A significant increment was found in the band gap till 40 GPa as compared to higher pressure. Under the effect of pressures ranging from 0 to 100 GPa, several optical properties like the refractive index, loss function, reflectivity, and absorption coefficient have also been determined. The main peaks of dielectric function (real and imaginary), reflectivity, loss function, and refractive index (n) are observed to move towards higher values of energy with increasing pressure. A material that has a high optical conductivity, absorption, and refractive index is ideal for photovoltaic applications. Other optical technologies that use such material include waveguides, data storage medium, and photonic crystals.