垒层Si掺杂对多量子阱InGaN绿光LED性能的影响

Effects of Si-doping in Barriers on the Performance of InGaN-based MQW Green LEDs

摘要:

InGaN系绿光LED的量子阱结构具有较高的In含量,InN与GaN之间较大的晶格失配度使得绿光器件的量子限制Stark效应更显著。对内建电场的屏蔽可以有效提高载流子的辐射复合效率。论文探讨了绿光多量子阱中垒层的Si掺杂对绿光器件性能的影响。研究发现,多量子阱中垒层适度Si掺杂(3.4×1016 cm-3)可以改善多量子阱结构界面质量和In组分波动,在外加正向电流的作用下更大程度地屏蔽极化电场;同时,还能够增强电流的横向扩展性,提高活化区的有效发光面积。然而,多量子阱中垒层的过度Si掺杂对于绿光LED器件的性能带来诸多的负面影响,比如加剧阱垒晶格失配、漏电途径明显增加等,致使器件光效大幅度降低。

Abstract:

The high fraction of indium (In) in the multi-quantum wells (MQWs) and the large lattice mismatch between InN and GaN make quantum confinement Stark effect (QCSE) more remarkable in InGaN-based MQW green LEDs. The shielding of the built-in electric field caused by QCSE can effectively improve the efficiency of carrier radiative recombination in LEDs. The effects of the Si-doping in barriers of MQWs on the performance of green LEDs were investigated. It is found that a moderate Si doping of (3.4×10¹⁶cm^-3) can effectively increase the interface quality of MQWs structure, reduce the In concentration fluctuation, and also shield the polarized electric field when a forward current is applied. Meanwhile, the transverse expansibility of current is also enhanced and the light-emitting area in active region is increased. However, too much Si-doping in the barriers of MQWs results in a series of harmful effects on the performance of green LEDs, such as larger lattice mismatch between wells and barriers in MQWs and higher leakage current, which deteriorates the luminous efficiency of LEDs.