The Investigation Of Preparation Process And Properties Of ZnO Films Via SOL-GEL Technique

ZnO is a II-VI semiconductor material with wide direct band gap of 3 .37eV and a large exciton binding energy of 60meV. For its large binding energy, the exciton is stable even in the room temperature. So it is considered as a promising material for light-emitting devices and semiconductor lasers with low thresholds in the UV region. All above excellent properties and application of ZnO highly depend on the preparation of high quality ZnO films with low cost.Sol-Gel method is used to fabricate ZnO films with high quality in the thesis. The main job of this thesis is focused on the deposition of ZnO films on the quartz plate and the influence of solvents and heat treatment process on the structural and optical property of ZnO films. We also try to explain the emission mechanism of UV and visible light of ZnO films at room temperature in this thesis.In chapter one, a comprehensive introduction of ZnO material is presented including the structure and basic properties of ZnO, growth technologies, potential applications.At last, the significance and characteristic of this thesis is given.In chapter two, brief information of the SOL-GEL Technique is listed such as history, basic principle and methods of fabricating films via SOL-GEL Technique.In the end of this chapter, the mechanisms of the measurements applied in the whole process of investigation of ZnO films are also introduced.In chapter three, the influence of solvents on the properties of ZnO films such as structure, morphology and optical properties is given. 2-methoxyethanol (EGME) is found to be a better solvent for a high quality of ZnO films.In chapter four, the post-annealing treatment of ZnO films using EGME as solvent with three-steps is investigated in detail. It is found that the post-annealing temperature at 650℃is suitable to ZnO film with high quality and excellent optical properties.In chapter five, the influence of pre-heat treatment on the structure and PL characterstic of ZnO films by two-steps is studied. The emission mechanism of undoped ZnO films and Al-doped ZnO films at room temperature is profoundly discussed in this chapter by studying temperature-dependent photoluminescence of the samples. In chapter six, a summary of this dissertation and suggestions for further study are listed.