Study On Preparation And Properties Of Metal-Via Compound Semiconductor Thin Films

Solar cell is one of the most effective method to resolve the energy and environmental problems, but the electrical cost of solar cell is relatively high, which limits its large-scale application. Thus, exploring the low cost preparation and materials to decrease the cost of solar cells has practical value. In this thesis, we prepared low cost oxygen compound semiconductor thin film materials by low cost methods (polyol and chemical bath deposition method). It might provide a new method to the subsequent preparation of low-cost solar cells. The main conclusions obtained in this work were listed as follows:(1) CdS thin films were successfully deposited onto glass substrates for the first time by polyol method using cadmium acetate as the cadmium source, thiourea as the sulfur source and diethylene glycol as the solvent. The influence of the preparation on the properties of the thin films was studied. The results showed that when the sulfur cadmium concentration ratio was increased, the trend of the thickness was first increased and then decreased, which was opposite to the trend of the transmittance. And a part of CdS particles were petal when the molar ratio was1:5and1:2. With the molar ratio continued to increase, the average grain size of CdS particles was decreased. When the deposition time was increased, both of the thickness and particle size of the thin films were increased, but the transmittance was decreased. The reaction was almost stopped when the deposition time was over70min. When the deposition temperature was increased, the trend of the thickness was first increased and then decreased, which was opposite to the trend of the transmittance. With the increasing deposition temperature, the average roughness was reduced and the surface of CdS thin films was smoother. In addition, the band gap of CdS thin films were prepared under different conditions was slightly larger than CdS block.(2) CU2O thin films were successfully deposited onto glass substrates by polyol method using copper nitrate as the copper source and ethylene glycol as solvent and reducing agent. The influence of the preparation on the properties of the thin films was studied. The results showed that both of the thickness and particle size of the thin films were increased and the transmittance was decreased when the concentration of copper source was increased. But the pore of the thin film became bigger and the coverage fraction of substrate was decreased. When the deposition time was increased, both of the thickness and particle size of the thin film were increased, but the transmittance was decreased and the pore between the particles was increased. The particles were isolated and did not connect to be the film. When the deposition temperature was increased, the trend of the thickness and particle size of the thin films were first decreased and then increased, which was opposite to the trend of the transmittance. In addition, all of CU2O thin films were prepared under different conditions were cubic crystal structure and their band gap was larger than CU2O block.(3) CuS thin films were successfully deposited onto glass substrates by chemical bath deposition method using copper chloride as the copper source, thiourea as the sulfur source, ammonia provided hydroxide ions and triethanolamine (TEA) as the complexing agent. The effect of the preparation on the properties of the thin films was studied. The results showed that when the sulfur copper concentration ratio was increased, the thickness of the thin films was similar except the concentration ratio was3:1, and trend of the average grain size was decreased. When the triethanolamine content was increased, both of the thickness and particle size of the thin films were increased, but the transmittance was decreased and the pore between the particles became bigger. When the triethanolamine content was more than7ml, the average grain size of CuS particles was more than300nm. When the ammonia content was increased, both of the thickness and particle size of the thin films were increased, but the transmittance was decreased and the pore between the particles became bigger. When the ammonia content was more than9ml, the average grain size of CuS particles was more than400nm. In addition, all of CuS thin films were prepared under different conditions were hexagonal crystal structure and their band gap was larger than CuS block.(4) After studying the deposition mechanisms of these three systems, we found that when the thin films were grown in solution, the thin films were composed by particles and the particles were almost spherical or ellipsoidal. The particles were growing and connect with each other to be the film, which was agreed with island growth characteristics. So, the film growth mechanism of all three systems can be considered as ion-ion growth mechanism. At the same time, the particles generated by homogeneous deposition were also adsorbed on the surface of the thin films in solution, but the adhesion was weak and could be cleaned by ultrasound.