A New Route for the Synthesis of CdS Thin Films from Acidic Chemical Baths

Well adherent nanocrystalline cadmium sulphide thin films have been successfully deposited from acidic chemical baths by employing tartaric acid and hydrazine as complexing agents for the first time. The pH of the bath was about 2.35 and the depositions were carried out at bath temperatures of 60 °C and 70 °C. The films were characterized by a variety of techniques. Powder X-ray diffraction patterns of the films exhibited a well crystallized hexagonal structure with a preferred orientation along the (002) plane. Scanning electron microscope investigation showed that the films are formed from spherically shaped grains. The EDAX result revealed that the deposited films had very good stoichiometry. The band gap of the thin films obtained by optical absorption spectroscopy, were 4.12 eV for the films deposited at 60 °C and 3.89 eV for films deposited at 70 °C. This unusual large band gap could be attributed to size quantization effects obtained by this new synthesis route