Increased Size of Open Hexagonally Shaped Pits due to Growth Interruption and Its Influence on InGaN/GaN Quantum-Well Structures Grown by Metalorganic Vapor Phase Epitaxy

We have investigated the influence of growth interruption when group-III sources are temporarily shut off, and that of the number of quantum-well (QW) layers, on the crystalline quality of InGaN/GaN QW structures grown by metalorganic vapor phase epitaxy. Atomic force microscopy measurements revealed that the size of the pits on the QW surface increased dramatically as the interruption time increased. Through transmission electron microscopy and energy dispersive x-ray microanalysis, we found that the pit formation due to growth interruption induces fluctuation in the In composition around the pits in the QW structure, which leads to significant variation in the growth rate as the number of QW layers increases.