Deposition of cadmium sulfide and cadmium selenide thin films using chemical bath deposition technique

A simple, convenient and low cost chemical synthesis technique, chemical bath deposition, are used to deposit cadmium sulfide (CdS) and cadmium selenide (CdSe) quantum dots on glass substrates. Based our characterizations, high quality CdS and CdSe thin films have been deposited on the substrates. In order to synthsize CdS quantum dots on glass, we use cadmium sulfate (CdSO₄), ammonia water (NH₄OH) and thiourea (CS(NH₂)₂) as reaction agents. For CdSe thin films, we use cadmium acetate as cadmium ion source and sodium selenosulfate / thiourea as a selenium / sulfur ion sources. Aqueous ammonia is used as a complex reagent and also to adjust the pH of the final solution. The asdeposited thin films using this technique are optically transparent, adherent, homogeneous and yellowish for CdS and redish for CdSe without powdered precipitation. The deposition can be made at 60 – 70°C under magnetic stirring for all samples. The films have been characterized by X-ray diffraction, scanning electron microscope (SEM), and UV-Vis absorption. The SEM measurements show that the shapes of deposited CdSe nanoparticles on glass substrates can be controlled to exhibit different shapes under different reaction conditions.