Comparative study of chemically deposited CdS thin films and of the non-synthesized CdSO4 under pressure and temperature within first principles

Abstract

CdS in its various crystal structures, has been intensively studied both theoretically and experimentally for their extensive industrial application. A Self-consistent calculation within Density Functional Theory (DFT) using norm-conserving pseudopotential plane wave and the precise hybrid functional HSE06. The stability, elastic, mechanical, electronic, and optical properties of CdSO4, h-CdS and c-CdS are theoretically investigated. Besides, structural and the optical properties of h-CdS thin films were experimentally studied by growing h-CdS thin films using chemical bath deposition (CBD) technique which is well suited for the manufacture of film solar cells. A study of the behavior of the stability and elastic characteristics under hydrostatic pressure is also presented. Band structure analysis using HSE06 and the absorption surface show that CdSO4 and c-CdS hold indirect bandgap while h-CdS is direct bandgap semiconductors. The structures are most stable at the computed relaxed lattice parameter a=b=4.250Ao, c=6.667 Ao for CdSO4, a=b=4.122 Ao, c=6.660 Ao for and h-CdS and a=b= c= 3.804 Ao for c-CdS. The Pressure dependence of cubic perovskite elastic moduli, bulk modulus B, shear modulus/constant (G, Cs), Young’s modulus E, the Poisson’s ratio σ, Vickers hardness Hv, Lame’s constants (λ, μ), Cauchy pressure C12-C44, the Anisotropy factor A, Kleinman parameter ζ, and the P-wave modulus Pw, elastic wave velocities v, Debye temperature θD is presented. The optical properties, both the static refractive index and dielectric constant are found to be related proportionally to the direct bandgaps. The refractive index, extinction coefficient, complex dielectric function, energy loss function, optical conductivity, reflectivity and absorption coefficient for 0–40 eV incident photon energies is presented.