Research On Formation Of One-Dimensional GaN And Ga₂O₃ Nanostructures Ammoniating Ga₂O₃/V On Si Substrates

Along with the development of science and technology, the materials with the more excellent properties are becoming more and more popular and the micromation for the devices is being current. These promote that the people are greatly interested in the research of low-dimensional materials. There are three points in the research of low-dimensional materials: (1) simplified description on the physical phenomena occurred in the three-dimensional materials; (2) to find the unique physical phenomena and properties of low-dimensional materials; (3) synthesis of new three-dimensional materials from low-dimensional materials. Since the discovery of the carbon nanotubes in 1991, materials with nanotube, nanowire and nanorod structures have been extensively investigated for their interesting and novel properties. They have unique structures. On the other hand, many novel physical properties such as Quantum Interference Effects in electrical properties, Quantum Confinement Effects in optical properties and the enhancement of mechanical properties, occur, which are different from the block materials. Nanomaterials are important for basic theory research and preparation of nano-devices. Take carbon nanotubes for examples, it has been proved that it can be used to prepare high-light field-emission electron source, nano-leads, nano-cuvettes, nano-probes and nano-balance for weighing up the micrograins. It is found that single-wall carbon nanotubes have the superconductivity. And that M-S heterojunction devices, which are made of carbon nanotubes and silicon nanowires, have rectigying effect.Wide-band gap gallium nitride (GaN) is one of the direct gap semiconductors and band gap is 3.4 eV at home temperature. It is the perfect material for preparing blue and green light-emission diodes and semiconductor laser. The theory and experiments show that GaN nanostructures markedly improve the luminescence properties of the devices. These lay a foundation for preparing high-integration and high-quality photoelectron devices. Nanostructure ofβ-Ga₂O₃ have recently attracted considerable attention as materials for the new generation of optoelectronic devices, since the crystals are transparent in a wide range of UV down to 280 nm and they are potentially electro-conductive. These characteristics are due to their band gaps of about Eg = 4.8 eV and n-type conductivity which has been attributed to the existence of oxygen vacancies when crystals are grown under reducing conditions. The gallium oxide compound semiconductor has been widely studied not only for their high stability and tenability in optical properties, but also for applications in high sensitive oxygen gas sensors working at high temperature , and transparent conductors in optoelectronics.GaN nanostructures were fabricated on Si(111) substrates through ammoniating Ga₂O₃/V films deposited by magnetron sputtering system. The structure, elemental composition and morphology of the GaN nanostructures were determined by X-ray diffraction(XRD), Fourier transformed infrared spectroscopy(FTIR), X-ray photoelectron energy spectroscopy (XPS), scanning electronic microscope (SEM) and high-resolution transmission electronic microscope (HRTEM). The results indicated that the as-synthesized GaN nanostructures were hexagonal GaN with wurtzite structure.The crystalline quality and morphology of GaN nanostructures were greatly influnced by the ammoniating temperature and the thickness of the V films. With the increase of temperature, the crystalline quality of GaN nanostructures was improved and the diameter of these nanowires was also increased. A VS mechanism was still valid in the growth process of GaN nanostructures in this method. The surface energy distribution of the substrate was greatly changed by the V films, which may plays an important role in the formation of GaN nanostructures.β-Ga₂O₃ nanostructured materials have been obtained on Si(111) substrates by annealing the Ga₂O₃/V films at different temperature. X-ray diffraction (XRD), scanning electron microscope (SEM) and high-resolution transmission electron microscope (HRTEM) are used to analyze the structure, morphology and optical property of Ga₂O₃ nanostructured films. The results indicated that the crystallization of Ga₂O₃ films on V middle layers was excellent. Besides, we also find that these Ga₂O₃ nanostructures were greatly influnced by the ammoniating temperature, the ammoniating time and the thickness of middle layer. The reason was V2O5 begins to release O2 over the temperature of 700°C. The effects of V middle layer on the synthesis of Ga₂O₃ nanostructures are also attributed to the change of the surface energy distribution.