Étude des propriétés structurales, électroniques et optiques de l'alliage binaire MoX2 (X=S, Se et Te) par la méthode ab-initio

Abstract

The present work explores the structural, electronic and optical properties of the wurtzite MoX2 (X=S, Se, Te) binary alloys. The calculations were performed using density functional theory (DFT) within full-potential linearized augmented planes waves (FP-LAPW) method implemented in the Wien2k package. First, the structural properties such as the lattices parameters a andc with bulk modulus B and first pressure derivative B’ are determined from three distinguished approximations PBE-GGA, PW- LAD and WC-GGA. When X is moved at S, Se and Te atoms the lattice a increases and c parameter increases. Second, the electronic properties like direct and indirect bandgap of MoS2 , MoSe2 and MoTe2 are investigated using both PBE-GGA and TB-mBJ approximations. The results shows that the binary alloys are semiconductors with direct bandgap energy. The gap decreases if X moves to S, Se and Te atoms. Third, the optical properties such as real and imaginary parts with the refractive index of the ternary alloys are predicted in this study. The curves of optical properties shift toward the higher energies with augmentation in their amplitudes.