The Preparation And Characterization Of Sulfide Thin Films And Powder Materials

Zinc sulfide (ZnS) is the group II-VI compound semiconductors with direct band gap energies covering 3.6³.8 eV. It is a promising optoelectronic material which has been used extensively in varieties of optics and photoelectrical devices such as thin film electroluminescent devices, laser diodes, blue light detectors and solar cells et al, especially as an n-type window layer for thin film solar cells based on copper indium diselenide, ZnS has increasingly taken the place of CdS for high conversion efficiency with low toxicity and environmental protection. ZnS-based material is doped, which is obtained in luminescence wave band from visible light to ultraviolet radiation. ZnS:Mn thin film has the best optical property.In this paper Zinc sulfide and ZnS:Mn thin films were prepared on glass slides by SILAR(successive ionic layer adsorption and reaction)method. The effects of the technological parameters on the quality of the films were studied. The growth rate and surface morphology of the films with cycle times were characterized. The effect of annealing on crystal structure of the films were studied. The size of the particles on the film surface is increased with the cycle times. The films as-deposited are amorphous and compact, the crystallity of the films were enhanced with the increase of the temperature. The results indicated that the specimen materials were ZnS thin film with cube and hexagonal structure unit. The contents of the ZnS films are not stoichimometric because of formation of Zn-O bond.Polycrystalline ZnS nanopowders were successfully prepared by the ultrasonic-assisted synthetic method using sodium sulphide hydrate (Na₂S·9H₂O) and stannous chloride hydrate (ZnCl₂·2H₂O) as raw materials. The specimen materials were characterized by X-ray diffraction,transmission electron microscopy and transmission electron diffraction. The results indicated that the specimen materials were ZnS polycrystalline powders with cube sphalerite structure unit, and the powders grain size was about 8¹2nm.