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

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.