| Gallium nitride (GaN) is an excellent chemical semiconductor material and also is one of the most advanced semiconductors in the world. In fact, GaN has been regarded as one of the most promising materials for the fabrication of opto-electronic devices operating in the blue and near-ultraviolet (UV) regions, for instance light-emitting diodes (LEDs) and laser diodes (LDs), because it has large direct energy band gap of 3.4eV at room temperature. In addition, GaN has been attracted much attention as a candidate for fabrication of high temperature, high frequency and high power devices. After 1990, the realization of some pivotally technical methods and the development of materials growth and devices technics made GaN to be the research focus of the world. MOCVD, MBE and HVPE have become dominating techniques to grow GaN materials. Among these methods, MOCVD is the most important and widely used by researchers. But now large-scale application of GaN devices is confined for the reason of costly equipments and complicated technics. Many research institutes and universities in the world are trying to grow GaN materials with simple and low cost methods.In this paper, firstly, we reported that GaN films are obtained on Si substrates by hot-wall chemical vapor deposition prepared by ourselves. Secondly, we reported high quality GaN films are prepared on Ga-diffused Si (111) substrates by the two-step growth method. The Ga-diffused Si substrates are suitable for the growth of GaN films because it can decrease the mismatch between GaN films and Si substrates and reduce the defects of formed GaN films.In the first chapter, the fundamental properties, the main application, and the growth technique of GaN films are introduced. In addition, we depict the investigationprogress and give the cause for selecting a subject.In the second chapter, the experimental instruments and the means to characterize the as-formed samples are introduced. In section 1, the experiment system including the oxidation system, diffusion system and the radio frequency magnetron sputtering system are introduced. In section 2, the measurement technique are introduced. The structure properties of the samples were examined by a Rigaku (Tokyo, Japan) D/max rB X-ray diffraction (XRD) meter with Cu Ka radiation (A,=l.54178 A). The composition of the sample were analyzed in a MICROLAB MKII X-ray photoelectron spectroscopy (XPS) using a monochromatized Mg Ka radiation with a take-off angle of 75 and a Nicolet 710 Fourier transform infrared (FTIR) system in a transmission mode. Images were obtained using a Hitachi H-8010 scanning electron microscopy (SEM), Hitachi H-800 transmission electron microscopy system (TEM), and Philip Tecnai20U-TWIN high resolution transmission electron microscopy (HRTEM) system. Photoluminescence (PL) spectra of the films were measured in the FLS920 fluorescence spectrophotometer at room temperature.In the third chapter, GaN films were obtained by the hot-wall chemical vapor deposition. We investigate the effect of growth time, the different reaction gases and growth temperature on the properties of GaN films.In section 1, GaN powder can be successfully synthesized by ammoniating Ga2O3 under high temperature. The results indicated that hexagonal GaN particales with high crystallization and high purity were obtained at the Ga source temperature of 850C.In section 2, 3, 4, in view of the mechanism of synthesizing GaN powder by ammoniating Ga2O3 under high temperature, GaN films were obtained on Si substrates by the hot-wall chemical vapor deposition. The results show that it is very difficult to obtain compact GaN films when only use NH3 as reaction gases, and the micro-crystal composed of micro-grains appear on the surface of the samples. But the crystal quality and the morphology of the GaN films can be improved obviously when introduce some H2 into the NH3 as reaction gases. In addition, the growth temperature also play an import role in the growth process of GaN films, the optimum growth temperature is 1050 C.In t...
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