Effect of sintering aid (CdCl2) on the optical and structural properties of CdZnS screen-printed film

Sulphides of zinc and cadmium have been utilized effectively in various opto-electronic devices. In the present work cadmium zinc sulphide (Cd_0.4Zn_0.6S) thin film has been deposited on ultra clean glass substrate by a simple inexpensive screen-printing method using cadmium sulphide, zinc sulphide, anhydrous cadmium chloride and ethylene glycol. Cadmium chloride has been used as sintering aid and ethylene glycol as a binder. Effect of sintering aid on the optical and structural properties of prepared cadmium zinc sulphide film has been investigated. The optical band gap (E_g) of the film has been studied by using reflection spectra in wavelength range 325–600 nm. It is found that reflection spectra suffer a drastic fall at two places, which is indicative of two band gaps of film viz. 2.38 eV and 2.9 eV corresponding to CdS and Cd_0.6Zn_0.4S, respectively. This is suggestive of the fact that cadmium zinc sulphide is a wide band gap semiconducting material. X-ray diffraction also confirms the formation of Cd_0.6Zn_0.4S composition.