Observation of structural defects in GaN/InGaN multi-quantum wells grown on semipolar (1122) substrate using cathodoluminescence in transmission electron microscopy

Defect structures of semipolar GaN thin film, grown on the m-plane of sapphire, were investigated using the home-built cathodoluminescence (CL) stage in TEM. The CL maps with high spatial resolution identify the type of basal plane stacking faults (BSFs) and visualize their distribution. I-1-BSF type defects had the highest population and the I-2-BSF type defect was revealed in the form of thin strips with less population. Partial dislocations and basal stacking fault-related defects existed in the form of segmented lines but with strong luminescence characteristics. TEM-CL was able to identify the distribution and the characteristic luminescence from the defects, which were difficult to discern in the typical defect analysis.