Studies and Characterization of ZnS Thin Films

The II-VI compound semiconductors are of great importance due to their application in various electro-optic devices. Thin films of ZnS find many more applications in the area of opto electronic device fabrication like UV light emitting diodes, blue light emitting diodes, emissive flat screens, electroluminescent devices and antireflection coating in solar cell technology. Several methods have been used to prepare ZnS thin films. We have deposited ZnS films using chemical bath deposition method using sodium hydroxide as a complexing agent. The structural and morphological characteristics of films have been investigated by X-ray diffraction (XRD) and scanning electron microscope. XRD shows deposited film was polycrystalline nature with cubic structure. The grain size is estimated to be in the range of 35-70 nm. The crystallinity of the ZnS film was analysed by HRTEM with the help of the electron diffraction pattern. The films show good optical properties with high transmittance in the visible region and the band gap value were found 3.3 eV - 2.1 eV. ZnS films can be used as buffer layers on CdTe solar cells.