AB INITIO STUDY OF OPTOELECTRONIC PROPERTIES OF SPINEL ZnAl 2 O 4 BEYOND GGA AND LDA

Electronic band structure and optical parameters of ZnAl 2 O 4 are investigated by first-principles technique based on a new potential approximation, known as modified Becke–Johnson (mBJ). This method describes the excited states of insulators and semiconductors more accurately The recent direct band gap result by EV-GGA is underestimated by about 15% compared to our band gap value using mBJ-GGA. The value of the band gap of ZnAl 2 O 4 decreases as follows: Eg (mBJ-GGA/LDA) > Eg (GGA) > Eg (LDA) . The band structure base optical parametric quantities (dielectric constant, index of refraction, reflectivity and optical conductivity) are also calculated, and their variations with energy range are discussed. The first critical point (optical absorption's edge) in ZnAl 2 O 4 occurs at about 5.26 eV in case of mBJ. This study about the optoelectronic properties indicates that ZnAl 2 O 4 can be used in optical devices.