| The technology of semiconductor thin film is the most effective measure to realize micromation of electronic device and system. The domestic and foreign researchers have focused on semiconductor thin film because it is widely applied to microelectron and photoelectron device. The microstructure of film material is influenced by preparation process. Therefore, macroscopic parameters such as growth process, the aggregation state are modulated, which influence atomic structure and the width of band gap to improve the physical property of film material. This has vital significance to development of materials science as well as the practical application of material.In this thesis, GaAs, GaN, ZnO semiconductor film materials were chosen as the objective of our studies, which are the key materials in red, blue, ultraviolet light LED, and the material used in LED process. Samples of various morphologies were prepared by CVD, carbon thermal reduction, hydrothermal and sol-gel method, and characterized by FESEM, HRTEM, XRD, PL, XPS, EDS and SAED. Relations between preparation process, microscopic structure, and physical properties were explored. The controllable modulation of property can satisfy multiple requests of photoelectron device. The conclusions are as follows:The GaAs/Ga2O3 polycrystalline thin film on gallium arsenic substrate was of regular wave shape in surface morphology; giving red emitting with high photoluminescence. Oxygen existed in two forms of deep level defect and gallium oxide. The formation mechanism of thin film was discussed.A series of GaN polycrystalline thin layers were grown on different substrates. Different growth parameters were used to improve the crystal quality and optical property. The results show that:First, higher growth temperature, lower NH3 flow rate and the presence of catalyst improved the crystal quality of GaN films. Second, the quality of GaN films was also improved by growing GaN on Al buffer layers deposited prior to growth, as was confirmed from PL spectra. Third, the thin films consisted of nanorod, nanobelt, nanowire, nanosheet, and nanoparticle. The Influence of experimental parameters were investigated.Three kinds of ZnO crystal powder prepared under various reaction temperatures were all wurtzite. Results show that the growth of three kinds of crystal complied with the basic structural unit theory for the growth of negative ion coordination polyhedron. At the same experimental conditions, hexagonal tubular zinc oxide crystal powder was prepared only through changing the proportion of source materials. Growth mechanism of ZnO tubes was found to be nanosheet curling. Photoluminescence property of the tube powder was stronger than that of raw materials. ZnO nano-polycrystalline thin films were all of hexagonal wurtzite structure. With different annealing temperature and substrate type, the thin films had different crystallization, photoluminescence intensity, and the emission position. The film on silicon substrate only had intrinsic emitting peak, but the film on glass substrate also showed emitting peak in visible light range besides intrinsic emitting peak.Reaction temperature and organic source type had crucial influences on the formation of flower-like vanadium carbide (V8C7) hierarchical nanocrystals. A possible growth mechanism of oriented adsorption was proposed. This kind of vanadium carbide can effectively enhance the dissociation rate of NH3, and thus probably play key role in synthesizing GaN crystal at low temperatures.Nanoropes composed of boron carbide and carbon grown on graphite substrate had such a structure that a single crystal wire of boron carbide in the center was covered with amorphous carbon knots. Growth mechanism of the nanoropes was discussed. The product is hopefully applied as cutting and polishing material in the fabrication of blue light LED. |
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