Influence of preparation conditions on the properties of silver doped copper-zinc sulfide thin films prepared via sol-gel spin coating technique

•Sol-Gel spin coating method was applied to synthesize Ag-doped CZS thin films.•The annealed samples at 320˚C have more crystallinity and the sample S2, 5L has the biggest crystal size of about 86.4 nm.•The crystallinity of Ag-doped films is superior compared to the pristine film.•Formation of Nano-rods, shapes of ≈ 600 nm of the deposited pristine CZS thin film with 5 layers on n-type Si substrate and annealed at 320˚C.•The 1% Ag/CZS film with 5 layer thickness on glass gives the highest transmittance in 400 - 1100 nm region. This work reports the preparation of Ag/Cu-Zn-S nanocomposite thin films using a sol-gel spin coating technique without sulfurization. For comparison, a pure Cu-Zn-S (CZS) sample, as well as CZS embedded with silver nanoparticles of various thicknesses, grown on heated substrates at 280 °C and 320 °C, were well fabricated. Several films like pristine CZS and Ag/CZS with different Ag % (0.5, 1, and 2 %) were deposited on various kinds of substrates like glass, n-type and p-type silicon with 5 and 8 layer thicknesses. The impact of annealing temperature 320 °C of the prepared film on the surface morphology, optical, structural, and electrical properties of the deposited films on various kinds of substrates were investigated. The field emission scanning electron microscopy images displayed homogeneous spreading with a smooth uniform surface of the substrates. Formation of Nano-rods (≈ 600 nm) dimension of the deposited pristine film with 5 layers on n-Si and annealed at 320 °C was observed. The energy dispersive spectroscopy results confirmed that a trace amount of metals was presented in the film. The X-ray diffraction for pristine and Ag/CZS films depicted peaks confirming to the polycrystalline of hexagonal and cubic crystal structure. It was observed that the optical bandgap energy (Eg) reduces with increasing the thickness of the film. The values of the index of refraction (n), high frequency and optical static dielectric constants (ε͚, ε˳) of deposit films on Si and glass substrates through the calculation of Eg as a function of the Ag concentrations were also calculated.