Microstructure and Formation Mechanism of V-defects in the InGaN/GaN Multiple Quantum Wells with a High in Content

In the growth of InGaN/GaN multi-quantum well (MQW) by metal organic chemical vapor deposition (MOCVD), V-defects have been observed and investigated. From cross-sectional transmission electron microscopy, we found that all V-defects are not always connected with threading dislocations (TD) at their bottom. By increasing the indium composition in the InxGa1-xN well layer, many V defects are generated from the stacking mismatch boundaries. The formation mechanism of these defects has been discussed in terms of stress induced by lattice mismatch and reduced In incorporation on the {1011} planes in comparison to the (0001) surface. The V-defect is correlated with the localized excitonic recombination centers that give rise to a long-wavelength shoulder in photoluminescence (PL). The InGaN/GaN multi-quantum well (MQW) grown on the {1011} faceted sidewalls of the V-defects gave much lower emission energies than those of the c-plane multi-quantum well (MQW).