中文摘要：

利用金属有机化学气相沉积系统（MOCVD）,在蓝宝石的（0001）面采用不同的成核层生长温度,通过两步法获得不同质量的Ga N外延薄膜。利用HALL测试仪,高分辨X射线衍射仪（HRXRD）,原子力显微镜（AFM）和光致发光光谱仪（PL）对Ga N薄膜的表面形貌,位错密度,光学性能等进行表征,研究不同的成核温度对Ga N外延薄膜晶体质量的影响。结果表明,在成核层生长温度为650℃时,所得到的Ga N外延薄膜表面粗糙度和位错密度均达到最低,并且同时具有最高的带边发光峰强度,最高的载流子迁移率以及最低的载流子浓度。过低或过高的成核温度都会导致Ga N外延层的晶体质量和光电性能变差。

英文摘要：

The growth of GaN epitaxial thin films with different nucleation growth temperature was performed by a two-step metal-organic chemical vapor deposition （MOCVD） growth process on c-plane sapphire. The structure and morphology of GaN epitaxial thin films were studied by HALL, HRXRD, AFM and PL. The results show that the surface roughness and dislocation density of GaN epitaxial film reache the lowest, at the same time, the sample has the highest band edge peak intensity, carrier mobility and lowest carrier concentration when the growth temperature of nucleation layer is 650 ℃. The crystallographic, morphologic and optical properties of GaN epitaxial film will decline when the temperature is too high or too low.