用金属有机物气相外延（ Ｍ Ｏ Ｖ Ｐ Ｅ）方法在蓝宝石衬底上生长了不同厚度和不同退火过程的氮化镓（ Ｇａ Ｎ）缓冲层，以及在缓冲层上继续生长了 Ｇａ Ｎ 外延层．研究了这些缓冲层的结晶学、表面形貌和光学性质以及这些性质对 Ｇａ Ｎ 外延层的影响． 提出了一个模型以解释用 Ｍ Ｏ Ｖ Ｐ Ｅ 方法在蓝宝石衬底上生长 Ｇａ Ｎ 外延层时存在一个最佳缓冲层厚度这一实验结果 Gallium nitride (GaN) buffer layers with different thicknesses and different annealing processes were grown on sapphire substrate by Metal Organic Vapor Deposition (MOPVP) method, and the GaN epitaxial layer was continuously grown on the buffer layer. The crystallinity, surface topography and optical properties of these buffer layers and the effect of these properties on Ga N epitaxial layers were investigated. A model was proposed to explain the experimental results of an optimal buffer layer thickness for growing a Ga N epitaxial layer on a sapphire substrate by MOPPE