缺陷对InGaN/GaN蓝光发光二极管载流子注入的影响

Impact of defects on the carrier injection for InGaN/GaN blue light-emitting diodes

缺陷引起的非辐射复合会造成InGaN/GaN蓝光发光二极管(LED)的光功率和外量子效率(EQE)降低,为了揭示其背后的物理原因,本文研究了Shockley-Read-Hall(SRH)复合相关的电子和空穴在多量子阱(MQWs)区域的复合过程,以及缺陷对于载流子注入效率的影响。研究结果表明载流子的注入效率非常容易受到LED中缺陷的影响,尤其是在LED结构的p-GaN层和n-GaN层中。这将导致载流子被LED中的缺陷捕获,从而以非辐射复合的形式被大量消耗。最终,大大降低了载流子注入到多量子阱区域的效率,也正是由于这个原因导致了LED的外量子效率随之下降。此外,还研究了缺陷对漏电流的影响,研究结果表明缺陷可以作为LED的分流电阻,形成一个漏电通道,从而引起漏电流的产生。

The defect of Shockley-Read-Hall(SRH)nonradiative recombination will decrease the optical power and ex⁃ternal quantum efficiency(EQE)for the InGaN/GaN light-emitting diodes(LEDs).To reveal the reason,we model the SRH recombination from the process of electron-hole recombination in the multiple quantum wells(MQWs)and the ef⁃fect of defects on the carrier injection.We find that the carrier injection efficiency is very strongly affected by the de⁃fects.Particularly,in the p-GaN and n-GaN layers for LED structures,the carries are captured by the defects and the non⁃radiative recombination consumes carriers.This in turn degrades the carrier injection efficiency into the InGaN/GaN MQWs and the external quantum efficiency for LEDs.We also model the influence of the defects on the leakage current,and find that the defects serve as shunt resistance,thus providing the current leakage paths.