A stable aqueous electrolyte solution containing Cu(II) cations and (S CN) anions was prepared by adding EDTA(ethylenediamine tetraacetic acid disodiu m salt, C10H14N2O8Na2·2H2O) to chelate with Cu(II) cations. CuSCN films were el ectrodeposited on transparent ITO conducting substrates from as-prepared electro lyte solution. Deposition mechanisms of CuSCN at varied temperatures have been s tudied. The results indicate that electron quantum tunnel through CuSCN film pla ys a role and the dense thin film with nanocrystals was obtained at or below roo m temperature. However, at higher temperature, a thermally activated process was involved and a thick film was obtained. It has been calculated that the activat ion energy of the growth for crystals is 0.5 eV. XPS pattern shows that the elec trodeposited film is (SCN) in stoichiometric excess, indicating a p-type film. A s-prepared CuSCN film was with high transmittance (≥85%) in the visible optical range and the direct transition band gap was 3.7 eV.
CuInS2 thin films have been prepared by ion layer gas reaction (ILGAR) using C2H5OH as solvent, CuC1and InCl3 as reagents and H2S gas as sulfuration source. The effects of cationic concentrations and numbers of cycle on the properties of CuInS2 film were investigated. The chemical composition, crystalline structure, surface topography, deposited rate, optical and electronic properties of the films were characterized by X-ray diffractrometry (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), ultraviolet-visible spectrometry (UV-Vis) and Hall System. The results show that the crystalline of CuInS2 thin films and the deposition rate have been improved with the increase of cationic concentration, while CuxS segregation phases appear with further increasing cationic concentration. The deposition rate is close to constant as cationic concentration is fixed.CuInS2 thin film derived form lower cationic concentration is uniform, compact and good in adhesion to the substrates. The absorption coefficient of CuInS2 thin films is larger than 104 cm^-1, and the band gap Eg is in the range of 1.30-1.40 eV. The dark resisitivity of the thin film decreases from 50 to 10 Ω·cm and the carrier concentration ranges are over 10^16 cm^-3.
