Optoelectronic Properties of SiMg2O4 and GeMg2O4 through mBJ Approximation

Abstract

A first-principles technique capable of describing accurately the nearly excited states of semiconductors and insulators, namely the modified Becke-Johnson (mBJ) potential approximation, is used to investigate the electronic band structure and optical properties of spinel oxides: SiMg2O4 and GeMg2O4. The predicted band gaps using the mBJ approximation show a significant improvement over previous theoretical work using the common LDA and GGA. Band gap dependent optical parameters, like dielectric constant, index of refraction, reflectivity and optical conductivity are calculated and analyzed. The static dielectric constant and refractive index of GeMg2O4 are much larger than that of SiMg2O4. This comprehensive theoretical study of the optoelectronic properties predicts that herein studied materials can be effectively used in the optical devices working in major part of the spectrum.