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系统研究了低温成核层生长时间、高温生长时的V/III比以及生长温度对氢化物气相外延生长GaN膜晶体质量的影响.研究发现合适的低温成核层为后续高温生长提供成核中心,并能有效降低外延膜与衬底间的界面自由能,促进成核岛的横向生长;优化的V/III比和最佳生长温度有利于降低晶体缺陷密度,促进横向生长,增强外延膜的二维生长.利用扫描电子显微镜、原子力显微镜、高分辨X射线衍射、低温光致发光谱和室温拉曼光谱对优化条件下生长的GaN外延膜进行了结构和光电特性表征.测试结果表明,膜表面平整光滑,呈现二维生长模式表面形貌;(002)和(102)面摇摆曲线半高宽分别为317和343 arcsec;低温光致发光谱中近带边发射峰为3.478 eV附近的中性施主束缚激子发射峰,存在11 meV的蓝移,半高宽为10 meV,并且黄带发光强度很弱;常温拉曼光谱中E2(high)峰发生1.1 cm 1蓝移.结果表明,优化条件下生长的GaN外延膜具有良好的晶体质量和光电特性,但GaN膜中存在压应力.
The effect of growth temperature of low temperature nucleation layer, V / III ratio at high temperature and growth temperature on the quality of GaN films grown by vapor phase epitaxy of hydride was systematically investigated. It was found that a suitable low temperature nucleation layer provided a nucleation center for subsequent high temperature growth , And can effectively reduce the free energy of the interface between the epitaxial film and the substrate to promote the lateral growth of the nucleation island. Optimized V / III ratio and optimal growth temperature are beneficial to reduce the density of crystal defects, promote lateral growth and enhance the epitaxial film Dimensional growth.The structures and the photoelectric properties of GaN epitaxial films grown under optimized conditions were characterized by scanning electron microscopy, atomic force microscopy, high resolution X-ray diffraction, low temperature photoluminescence spectroscopy and room temperature Raman spectroscopy.The results show that the films The surface is flat and smooth, showing a two-dimensional growth pattern surface morphology; (002) and (102) plane rocking curve half-height width of 317 and 343 arcsec respectively; low-temperature photoluminescence spectrum near-edge emission peak near 3.478 eV The donor-bound bound exciton emission peak showed a blue shift of 11 meV with a FWHM of 10 meV and a weak yellow band emission intensity. The E2 (high) peak was blue-shifted at 1.1 cm 1 at room temperature in Raman spectrum. , GaN epitaxial films grown under optimal conditions has good crystal quality and optical characteristics, but the compressive stress present in the GaN film.