OPTICAL AND STRUCTURAL PROPERTIES OF ZnxCd1-xS (X=0.2, 0.4, 0.6 AND 0.8): THIN FILMS PREPARED BY THERMAL EVAPORATION TECHNIQUE

Thin films of ZnxCd1-xS (x=0.2, 0.4, 0.6 and 0.8) were deposited on cleaned soda lime glass substrates at room temperature by thermal evaporation technique, having source current 50-65 Ampere, chamber pressure 10-5Torr and deposition rate 0.4 nm/sec. These conditions were same for all the thin films having different zinc concentrations. UV-VIS Spectrophotometry was used to study the optical properties of thin films of ZnxCd1-xS in room temperature. XRD was used to study the structure of the thin films of ZnxCd1-xS having various composition of „x‟. UV-VIS studies revealed that as the concentration of zinc content increases, transmission spectra shift towards the shorter wavelength region from (575-526)nm, the percent transmittance was increased in the visible range with the increase of zinc content, absorption edges and absorption coefficient spectra also shift towards the shorter wavelength and hence the direct band gap energy varied non-linearly from 2.55ev to 2.84ev.It was also found that optical conductivity increases with photon energy and thin film of Zn0.4Cd0.6S has high optical conductivity as compared to other value of „x‟. The reflectance and optical constants such as the extinction coefficient and refractive index were also found to depend upon the zinc concentration in the films. XRD studies showed that all the thin films of ZnxCd1-xS (x= 0.2, 0.4, 0.6 and 0.8) had a strong peak in between the diffraction angle 26.60- 31.70, which confirmed that all the thin films exhibited the wurtzite structure with a preferential orientation of (002) plane. It was also found that lattice constants, inters planer spacing, volume and grain size decreases except for Zn0.4Cd0.6S thin film which had high crystallinity as compared to the other composition of the zinc content