Effect of V-shaped pits size on the emission efficiency of InGaN/GaN light emitting diodes
Chiao-Yun Chang1*, Heng Li1, Tien-Chang Lu1
1Department of Photonics & Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu, Taiwan
* presenting author:Chiao-Yun Chang, email:chiao0826@gmail.com
We invesstagated the emission efficiency for InGaN/GaN multiple quantum wells (MQWs) and the varying V-shape pits (V-pits) size on the top of the threading dislocation (TD). The thinner InGaN/GaN MQWs on the side walls around V-pits would create higher local energy barriers, which can resist the carriers trapped into the non-radiative recombination centres within TDs. By inserting different InGaN/GaN superlattice (SLS) layers below the MQWs, sizes of V-pits could be properly controlled. It was found that the V-pit size on InGaN MQWs increased with increasing SLS layers, which could cause to reduce emission efficiency. On the contrary, the smaller V-pit size lacks to resist the carrier capturing capability of TDs. Therefore, the optimal LED structure with 15 pairs SLS, it has largest energy barrier height at 2.81 eV and the internal quantum efficiency exhibits a significant enhancement (70%).

Keywords: V-pit defect, internal quantum efficiency (IQE), droop efficency