Study of ab initio calculations of structural, electronic and optical properties of ternary semiconductor ${\mathbf{G}\mathbf{a}}_{1-\mathbf{x}}{\mathbf{I}\mathbf{n}}_{\mathbf{x}}\mathbf{S}\mathbf{b}$ alloys

Abstract

First principles calculations of the structural, electronic and optical properties of GaSb, InSb and their ternary ${{\text{Ga}}}_{1-x}{{\text{In}}}_{x}{\text{Sb}}$ alloys (x = 0.25, 0.50 and 0.75) have been performed using the full-potential linear muffin-tin orbital (FP-LAPW) method within density functional theory (DFT). The generalized gradient approximation and modified Becke and Janson functional with local density approximation (mBJ–LDA) are utilized for the treatment of exchange and correlation potentials. The results show the calculated lattice constants increase linearity with increasing the In concentration. The electronic band structure indicates that these alloys are direct band gap semiconductors for all the values of x and the band gap decreases as x increases from x = 0 to x = 1. The results also show that the there is a non-linear dependence of the band gap on composition x in ${{\text{Ga}}}_{1-x}{{\text{In}}}_{x}{\text{Sb}}$ alloys. Regarding optical properties, the real and imaginary parts of the dielectric function have been calculated. The results show that the static dielectric constant increases with increase in concentration of In, consistent with reduction in energy band gap. The onset point and major peaks in the imaginary parts of the dielectric function spectra are identified for the ${{\text{Ga}}}_{1-x}{{\text{In}}}_{x}{\text{Sb}}$ alloys and shown that they are related to the corresponding band gap values. The results also show that for energy values higher than $\cong 4$ eV, the electromagnetic wave transition through ${{\text{Ga}}}_{1-x}{{\text{In}}}_{x}{\text{Sb}}$ alloys is nearly zero.