The Synthesis Of GaN Nano-materials By CVD

Ⅲ-Ⅴcompound semiconductor materials with wide band gap is represented by gallium initride (GaN), whoes energy band gap is 3.4eV. Due to the high saturated electronic drift velocity, high thermal conductivity, resistance to high temperature, rad resistance, resistance to acid and alkali, high hardness features, etc.. It is used to make the semiconductor devices, such as efficient blue-green light emitting diodes, blue-ray semiconductor laser, high power-high frequency Field Effect Transistors, and ultraviolet detectors. The GaN film is mainly used in practice. The researchers tried to produce the GaN films by different methods. HVPE was the earliest, and then MOCVD and MBE were used.At present, some new methods appear, such as electrophoresis deposition (EPD), pulse laser deposition (PLD), magnetron sputtering (MS), sol-gel (Sol-Gel), etc.. In this paper, chemical vapor deposition (CVD) with simple equipment, low cost and easy operation was adopted. The crystalline phase, structure, composition, morphology, and optical property of each sample were analyzed using High-Resolution X-Ray Diffraction (HRXRD), Field Emission Scanning Electron Microscope (FESEM), Atomic Force Microscopy (AFM), Energy Dispersive X-Ray Spectroscopy (EDS), and Photoluminescence (PL). Through the test results, we constantly optimized the preparation process to improve performance of products.Currently, except the GaN substrate, lattice mismatch and thermal expansion coefficient mismatch exist between other substrates and GaN nanomaterials. Therefore, the use of appropriate substract and buffer layer becomes the focus of attention of researchers. GaN films were deposited on different substrates and different GaN buffer layers by atmospheric pressure chemical vapor deposition (APCVD). The structure, composition and optical property of each sample were analyzed and the growth mechanism and influencing factors were discussed.In addition to GaN films, micro-nano materials with other morphologies also are applied in light-electronic devices. In this study, GaN micro/nano materials were prepared on Si (100) substrate by CVD with double catalyst mode using Au film and indium silk as auxiliaries. In the process, GaN micro/nano materials with different morphologies was obtained and the structure, catalyst role and growth mechanisms of the products were analyzed.1. The polycrystal GaN films were produced using gallium and ammonia as raw materials, Si, Al2O3 and GaAs as substrates. Due to the bad thermal stability of GaAs substrate and 850℃decomposition temperature of ammonia gas, the experiment was done under the temperature less than 870℃. The results showed that the product was polycrystal with six-party fine zinc mine structure. The crystallization property and optical property of GaN films on Al2O3 substrate were best; but GaN film on GaAs substrate was worst and delaminated.2. The GaN films grew at 1000℃, using gallium and ammonia as raw materials, Al and Au/Al as buffer layers. The density, crystallization property and luminous intensity of GaN films were improved by the buffer layers.3. GaN mico/nano materials were systhesized under the growth mode of double auxiliaries, using gold and indium as auxiliaries, gallium and ammonia gas as raw materials, by CVD method. GaN micro/nano materials with different morphologies were obtained. The influence of auxiliaries, reaction time, reaction temperature and ammonia flow on the product was studied.