Zhang Zi-Hui, Tian Kangkai, Chu Chunshuang, Fang Mengqian, Zhang Yonghui, Bi Wengang, Kuo Hao-Chung
Opt Express. 2018 Jul 9;26(14):17977-17987. doi: 10.1364/OE.26.017977.
This work establishes the relationship between the electron energy and the electron concentration within the multiple quantum wells (MQWs) for AlGaN based deep ultraviolet light-emitting diodes (DUV LEDs). The electron energy of different values can be obtained by modulating the Si doping concentration in the n-AlGaN layer and/or engineering the polarization induced interface charges. The modulated Si doping concentration in the n-AlGaN layer will cause the interface depletion region within which the electric field can be generated and then tunes the electron energy. The polarization induced charges and the polarization induced electric field can be obtained by stepwisely reducing the AlN composition for the n-AlGaN layer along the [0001] orientation. We find that the electron concentration in the MQWs can be increased once the electron energy is reduced to a proper level, which correspondingly improves the external quantum efficiency (EQE) for DUV LEDs. According to our investigations, it is more advisable to adopt the n-AlGaN layer with the stepwise AlN composition, which can make both the EQE and the wall plug efficiency high.
这项工作建立了基于AlGaN的深紫外发光二极管（DUV LED）多量子阱（MQW）内电子能量与电子浓度之间的关系。通过调节n-AlGaN层中的Si掺杂浓度和/或设计极化诱导界面电荷，可以获得不同值的电子能量。n-AlGaN层中调制的Si掺杂浓度会导致界面耗尽区，在该区域内可以产生电场，进而调节电子能量。通过沿[0001]方向逐步降低n-AlGaN层的AlN成分，可以获得极化诱导电荷和极化诱导电场。我们发现，一旦电子能量降低到适当水平，MQW中的电子浓度就会增加，这相应地提高了DUV LED的外量子效率（EQE）。根据我们的研究，采用具有逐步AlN成分的n-AlGaN层更为可取，这可以使EQE和壁插效率都很高。
