Exploring the optoelectronic properties of Nitrido-magneso-silicates: Ca[Mg3SiN4], Sr[Mg3SiN4], and Eu[Mg3SiN4]

Optoelectronic properties of the Nitrido-magneso-silicates Ca[Mg3SiN4], Sr[Mg3SiN4], and Eu[Mg3SiN4] compounds have been investigated using the relativistic full-potential augmented plane-wave method (FLAPW) based on the density functional theory (DFT). The calculations of the electronic and optical properties were conducted by using the local density approximation (LDA), generalized gradient approximation (GGA), and modified Becke Johnson (mBJ) potential. A study of the band structures shows that these compounds are indirect band gap materials. We found a great variation in the obtained energy band gap value as we changed the functionals. The mBJ functional leads to a greater band-gap value compared to LDA and GGA cases. Based on the calculated electronic structure, the optical properties computed, such as the complex dielectric function, absorption coefficient, reflectivity, energy loss function and refractive index, were functions of the photon energy. Origins of the spectral peaks in the optical spectra were discussed and assigned to different electronic transitions observed from the electronic structure calculation.