Surface morphological studies of green InGaN/GaN multi-quantum wells grown by using MOCVD

Surface morphology of green InGaN/GaN multi-quantum wells (MQWs) grown by using metal organic chemical vapor deposition has been analyzed by using atomic force microscopy, scanning electron microscopy, and cathodoluminescence (CL). Effects of barrier growth temperature, indium composition, and background threading dislocation (TD) density on the evolution of the MQW surface morphology have been studied. Low temperature GaN barrier growth generates a high density of V-pits and inclusions embedded within V-pits. Using trimethylindium flow prior to InGaN well growth, In segregation on GaN barrier is shown to be the prime cause for the formation of some inclusions which appear as bright spots in CL mapping while some inclusions are related to low temperature barrier growth. High temperature GaN barrier growth at 910 °C completely suppresses these inclusion defects. In high indium containing InGaN/GaN MQWs, the large lattice mismatch induced strain in the MQW plays the key role in producing V-pits as well as inclusion defects rather than the background TD density of GaN templates.