Preparation Of SnSe And Cu₂O Semiconductor Thin Film Materials By Electrochemical Methods And Analysis Of Their Composition And Morphology

In the thesis, the preparation of SnSe semiconductor thin films on a slice-like gold plane electrode and p-si (100) electrode by electrochemical deposition; and Cu₂O thin films prepared on ITO covered glass were reported. Electrochemical methods, X-ray diffraction (XRD), and X-ray photo spectroscopy (XPS) were used to study the deposition mechanisms of the thin films and to analyze the composition; atomic force microscopy (AFM), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) were used to study and characterize the thin films. The main contents are shown as follows:1. The formation of the compound SnSe on a slice-like gold plane electrode at room temperature by electrochemical atomic layer epitaxy (EC-ALE) is reported here. Cyclic Voltammetry (CV) was used to determine approximate deposition potentials, the relationship of deposition potentials and deposition cycles for each element. The amperometric i-t method was the main means to deposit the compound. Judging from the colors presented from the thin films, it was found that the thin films contain the properties of the photon crystals. At last, the film's structure was characterized by atomic force microscopy (AFM).2. A compound semiconductor SnSe was electrodeposited from aqueous solution on p-type silicon (100) wafer finished with H-atom. Cyclic Voltammetry (CV) was used to determine approximate deposition potential range for each element. It was found that SnSe was prepared only under illumination. The kinetics mechanism was consistent with cooperation of photocatalysis. Under illumination, however, electrons are photoexcited from the valence band to the conduction band; holes were formed in the valance band, and electron-hole pair's photogenerated in the interface of electrode and solution. If the energy levels of the conduction band and the redox potential of metal are appropriately situated, photoelectron will lead the depositon of Sn and Se, respectively. X-ray diffraction (XRD) showed that the SnSe films were single crystalline. Scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and atomic force microscopy (AFM) investigated the obtained SnSe thin film possessed a very regular and aligned structure.3. Cuprous oxide and copper thin films were potentiostatically electrodeposited over indium-tin oxide (ITO) coated glass substrate with two different aqueous electrolytes: 0.1 M KNO₃ solution in comparison with the 0.05M CH₃COOH/CH₃COONa (pH = 5.7) solution. Cyclic Voltammetry (CV) was used to determine the optimal deposition potentials. X-ray diffraction (XRD) and X-ray photo spectroscopy (XPS) revealed that the kinetics mechanism and composition of the thin films. Furthermore, the structural and morphological properties of the films have been investigated by means of scanning electron microscopy (SEM) and atomic force microscopy (AFM).