Growth of GaN epitaxial layers is optimized in an indigenously developed nitride metal organic vapour phase epitaxy (MOVPE) system. The motivation of present work is to develop a simple MOVPE reactor which is though affordable but can deliver GaN epilayers of desired quality. The design and fabrication methodology of nitride MOVPE system is briefly discussed. MOVPE growth of GaN epilayers is carried out through a two-step growth process where influence of the growth parameters of low temperature buffer layer on the crystalline properties of high temperature GaN epilayer is discussed in detail. Optimum values of the growth temperature, annealing duration and thickness of GaN buffer layer are achieved. High resolution X-ray diffraction measurements (HRXRD) confirmed that the crystalline quality of GaN epitaxial layers is reasonable. A good surface morphology of the optimized sample is strongly corroborated by the results obtained from photoluminescence (PL) and HRXRD techniques. Usefulness of a systematic Williamson-Hall analysis in the optimization of growth of GaN epitaxial layers is demonstrated where a high value of lateral coherence length of GaN buffer layer is found to be a key parameter. Such an optimization process leads to the good crystalline quality of GaN epitaxial layers with low dislocation density. It is found that the high temperature GaN epilayers grown on the optimized GaN buffer layer are compressively stressed which is also revealed by the PL measurements.

在本地开发的氮化物金属有机气相外延（MOVPE）系统中优化了GaN外延层的生长。当前工作的动机是开发一种简单的MOVPE反应器，该反应器虽然价格合理，但可以提供所需质量的GaN外延层。简要讨论了氮化物MOVPE系统的设计和制造方法。GaN外延层的MOVPE生长是通过两步生长过程进行的，其中详细讨论了低温缓冲层的生长参数对高温GaN外延层的晶体性能的影响。获得了GaN缓冲层的生长温度，退火持续时间和厚度的最佳值。高分辨率X射线衍射测量（HRXRD）证实GaN外延层的晶体质量是合理的。从光致发光（PL）和HRXRD技术获得的结果强烈证实了优化样品的良好表面形态。证明了系统的Williamson-Hall分析在优化GaN外延层生长中的有用性，其中发现GaN缓冲层的横向相干长度的高值是关键参数。这样的优化过程导致具有低位错密度的GaN外延层的良好晶体质量。发现在优化的GaN缓冲层上生长的高温GaN外延层受到压缩应力，这也通过PL测量显示出来。证明了系统的Williamson-Hall分析在优化GaN外延层生长中的有用性，其中发现GaN缓冲层的横向相干长度的高值是关键参数。这样的优化过程导致具有低位错密度的GaN外延层的良好晶体质量。发现在优化的GaN缓冲层上生长的高温GaN外延层受到压缩应力，这也通过PL测量显示出来。证明了系统的Williamson-Hall分析在优化GaN外延层生长中的有用性，其中发现GaN缓冲层的横向相干长度的高值是关键参数。这样的优化过程导致具有低位错密度的GaN外延层的良好晶体质量。发现在优化的GaN缓冲层上生长的高温GaN外延层受到压缩应力，这也通过PL测量显示出来。