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采用两步生长模式的金属有机化学气相沉积方法在蓝宝石衬底上外延生长AlN薄膜,通过高分辨X射线衍射和原子力显微镜分析方法,研究发现蓝宝石衬底上外延生长的AlN薄膜晶体质量与高温AlN形核层的形核密度及晶粒大小密切相关,而形核密度决定于高温AlN形核层的初始铝体积流量,晶粒的大小取决于其厚度。优化了高温AlN形核层的初始铝体积流量和厚度等工艺参数。当高温AlN形核层的初始铝体积流量为30 cm3/min、生长时间为9 min时,高温AlN形核层的形核密度和晶粒大小最优,外延生长的AlN薄膜位错密度最低,表面最平整,晶体质量最好。
AlN films were epitaxially grown on sapphire substrate by two-step metalorganic chemical vapor deposition (MOCVD). High-resolution X-ray diffraction and atomic force microscopy analysis revealed that the AlN films grown on the sapphire substrate were epitaxially grown on high-temperature AlN The nucleation density and the grain size of the nucleation layer are closely related, and the nucleation density depends on the initial aluminum volume flow of the high-temperature AlN nucleation layer. The size of the grains depends on the thickness. The process parameters such as initial aluminum volume flow rate and thickness of high temperature AlN nucleation layer were optimized. The nucleation density and grain size of high temperature AlN nucleation layer are the best when the initial aluminum volume flow rate is 30 cm3 / min and the growth time is 9 min. The dislocation density of epitaxial AlN film is the lowest, The most smooth surface, the best crystal quality.