First-principles calculations of structural, electronic and optical properties of CdxZn1−xS alloys

Structural, electronic and optical properties of ternary alloy system CdxZn1−xS have been studied using first-principles approach based on density functional theory. Electronic structure, density of states and energy band gap values for CdxZn1−xS are estimated in the range 0 ≤ x ≤ 1 using both the standard local density approximation (LDA) as well as the generalized gradient approximations (GGA) of Wu–Cohen (WC) for the exchange-correlation potential. It is observed that the direct band gap EgΓ−Γ of CdxZn1−xS decreases nonlinearly with the compositional parameter x, as observed experimentally. It is also found that Cd s and d, S p and Zn d states play a major role in determining the electronic properties of this alloy system. Furthermore, results for complex dielectric constant ɛ(ω), refractive index n(ω), normal-incidence reflectivity R(ω), absorption coefficient α(ω) and optical conductivity σ(ω) are also described in a wide range of the incident photon energy and compared with the existing experimental data.

Research highlights▶ The results presented in this paper are new and important, because technologically important II–VI mixed compounds have undergone many experimental and theoretical investigations. ▶ This paper covers various aspects of electronic and optical properties of CdxZn1−xS ternary alloys and provides predictions that may be useful in optoelectronic devices. ▶ Electronic structure, density of states and energy band gaps values for CdxZn1−xS are estimated in the range 0 ≤ x ≤ 1 using both the standard local density approximation (LDA) as well as the generalized gradient approximations (GGA) formalisms. ▶ Moreover, results for complex dielectric constant ɛ(ω), refractive index n(ω), normal-incidence reflectivity R(ω), absorption coefficient α(ω) and optical conductivity σ(ω) are also described in a wide range of the incident photon energy and compared with the existing experimental data.