AlGaN插入层对6H-SiC上金属有机物气相外延生长的GaN薄膜残余应力及表面形貌的影响

研究了具有不同台阶数目的AlGaN插入层对在6H-SiC衬底上利用金属有机物气相外延（MOVPE）生长的GaN体材料残余应力和表面形貌的影响.高分辨率X射线衍射测试表明样品的c轴晶格常数随台阶数目的增多而增大；低温光荧光谱中GaN发光峰也随着台阶数目增多而发生蓝移，这些变化都反映出GaN中残余张应力的减小.此外，原子力显微镜测试表明样品表面起伏和粗糙度也都随着插入层的引入和台阶数目的增多得到了明显的改善. 关键词： 残余应力 表面形貌 SiC衬底 AlGaN插入层

Effect of AIGaN intermediate layer on residual stress control and surface morphology of GaN grown on 6H-SiC substrate by metal organic vapour phase epitaxy

GaN layers with AlGaN intermediate layers of different Al mole fraction steps were grown on 6H-SiC by metal organic vapour phase epitaxy system. The residual stress and surface morphology of these samples were compared with GaN/AlN/SiC structure in detail. High resolution X-ray diffraction indicates that the c-axis constant increases with the increasing number of AlGaN steps, while low-temperature photoluminescence measurement shows a blue-shift of the GaN peak. These results should be attributed to the decreased residual stress in GaN. Furthermore, surface morphology of samples with AlGaN intermediate layers is improved according to the results of atomic force microscope.