Improved Photoluminescence in InGaN/GaN Strained Quantum Wells

The influence of strain accumulation on optical properties is investigated for InGaN/GaN-based blue light-emitting diodes grown by metal organic vapor-phase epitaxy. It is found that it is possible to reduce the strain relaxation and hence the nonradiative recombination centers in InGaN multi-quantum wells (MQWs) by adopting more InGaN/GaN MQWs pairs. The alleviation of strain relaxation in a superlattice layer results in the crystalline perfection and effective quality improvement of the epitaxial structures. With suitable control of the crystalline quality and reduced strain relaxation in the MQWs, there shows a 4-fold increase in light output luminous efficiency as compared to their conventional counterparts.