Improvement of structural and luminescence properties in InGaN/GaN multiple quantum wells by symmetrical thin low temperature-GaN layers

Abstract

InGaN/GaN quantum wells (QWs) with symmetrical ultra thin (about 0.5nm) low temperature GaN (LT-GaN) layers bounding each InGaN layer were grown by metal-organic vapor phase epitaxy (MOVPE). From the high resolution X-ray diffraction (HR-XRD) measurement, it showed improved well-barrier interface abruptness compared to the reference MQWs without the LT-GaN layers. In addition, the V-defect density and surface roughness were reduced, especially with the depth of V-defect as low as 0.7nm. Based on the temperature dependence photoluminescence (TDPL) experiments, the internal quantum efficiency (IQE) was increased from 21.2% to 30.1% by inserting the LT-GaN layers. The carrier lifetime obtained from room temperature time resolved photoluminescence (TRPL) measurement was 7.95ns, which was longer than 5.34ns for reference MQWs. These results indicated that these additional symmetrical thin LT-GaN layers enhanced the mobility of indium and gallium atoms as well as suppressed the indium desorption for growth high quality InGaN layers and in turn improved its structural and luminescence properties.