中文摘要：

通过研究蓝宝石衬底上HVPE-GaN的表面形貌,指导HVPE-GaN工艺。工艺是在自制的立式HVPE设备上进行的,通过显微镜观察了各种不同工艺条件下的GaN表面形貌。发现不采用成核层直接生长的GaN表面粗糙为多晶,而采用低温成核层所得到的GaN表面随着Ⅴ/Ⅲ比由大到小,从包状表面向坑状表面过渡,通过选择合适的Ⅴ/Ⅲ,可以得到表面光滑、无色透明的GaN。其XRD摇摆曲线半高宽为450 arcs,表面粗糙度为0.9 nm。

英文摘要：

Morphology of HVPE-GaN was used as a guidance of HVPE process. GaN was grown directly on sapphire by a domastic-built vertical HVPE system, and the surface morphology of GaN was studied. It was found that GaN layer was multi-crystal with rough surface when low-temperature nucleation layer was not used. With in-situ low-temperature nucleation layer, the HVPE GaN surface changed from surface with hills to pitted surface when Ⅴ/Ⅲ ratio decreased. If Ⅴ/Ⅲ ratio was set appropriately, smooth and colorless GaN layer, whose XRD FWHM is 450 arcs and Ra is 0.9 nm, could be grown on sapphire with in-situ low-temperature nucleation layer.