LM-IAI量子阱势垒GaN基LED性能提升研究

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"这篇文章主要探讨了GaN基发光二极管(LED)中采用晶格匹配InGaN / AlInN / InGaN量子阱势垒(LM-IAI)的设计，通过数值模拟分析了其性能提升的原因和潜力。" 在半导体照明领域，GaN基LED因其高效、节能的特性而广泛应用。传统的GaN基LED通常采用GaN作为势垒材料，然而，由于晶格失配问题，可能导致器件性能下降，如内部量子效率(IQE)低和发射功率不足。针对这一问题，该研究提出了一种新型设计，即使用晶格匹配InGaN / AlInN / InGaN量子阱势垒，以减少晶格失配带来的负面影响。作者通过数值模拟研究了这种LM-IAI结构对LED性能的影响。模拟结果显示，这种设计能够显著提高LED的IQE和发射功率。其中，量子限制的Stark效应的缓解是关键因素之一。量子限制的Stark效应会导致能级分裂，影响载流子的束缚状态，而LM-IAI结构能有效减轻这一效应，从而改善光发射效率。此外，LM-IAI结构还抑制了电子泄漏现象，这是另一个导致传统GaN基LED性能下降的重要原因。电子泄漏会降低载流子在量子阱中的停留时间，减少辐射复合，因此，抑制电子泄漏能增加光输出。更进一步，研究发现通过移除电子阻挡层，LM-IAI结构的GaN基LED性能还能得到提升。这是因为移除电子阻挡层可以增强空穴注入效率，空穴的高效注入能促进更多的电荷复合，进而提高辐射复合率。同时，空穴注入效率的提高也减少了整体的俄歇复合，俄歇复合是一种非辐射复合过程，会降低LED的发光效率。采用晶格匹配InGaN / AlInN / InGaN量子阱势垒的GaN基LED设计能够有效解决传统LED存在的问题，提高内部量子效率和发射功率，是LED技术的一种创新改进。未来的研究可能会继续探索优化这种结构的具体方法，以及如何将这些理论成果应用于实际制造过程中，以实现更高效、更稳定的LED器件。

1056 JOURNAL OF DISPLAY TECHNOLOGY, VOL. 11, NO. 12, DECEMBER 2015

Performance Analysis of GaN-Based Light-Emitting

Diodes With Lattice-Matched InGaN/AlInN/InGaN

Quantum-Well Barriers

Naiyin Wang, Student Member, IEEE, Yi An Yin, Bijun Zhao, and Ting Mei, Senior Member, IEEE

Abstract—In this paper, the properties of GaN-based light-emit-

ting diodes (LEDs) with lattice-matched InGaN/AlIn

N/InGaN

(LM-IAI) quantum-well (QW) barriers are investigated numeri-

cally. Distributions of electrostatic ﬁeld, carrier current density,

carrier concentration and radiative recombinati

on rate are simu-

lated, and internal quantum efﬁciency (IQE) and emission power

are calculated. The results show that the LEDs with LM-IAI

barriers have higher IQE and emission power ove

r their conven-

tional counterparts with GaN barriers due to the mitigation of

the quantum-conﬁned Stark effect and the suppression of electron

leakage. Furthermore, the performance

s of the nitride-based

LEDs with the proposed barriers can be further improved by

dismissing the electron-blocking layer, which is attributed to

the improvement of hole injection efﬁ

ciency and the decrease of

overall Auger recombination.

Index Terms—AlInN, light-emitting diodes (LEDs), multilayer

barrier, quantum efﬁciency (QE).

I. INTRODUCTION

MPROVING quantum efﬁciency (QE) is an eternal effort

for GaN-based light-emitting diodes (LEDs), since they

suffer from a severe efﬁciency droop and consequent low

QE at high drive current, which is a big obstacle for them to

be competitive in terms of high-brightness and high-power

applications as demanded in general lighting [1]–[3]. Among

the numerous mechanisms proposed, electron leakage [4],

[5], poor hole injection efﬁciency [6], [7], and Auger recom-

bination [8], [9] may play important roles for the problem.

The polarization ﬁeld from spontaneous and piezoelectric

polarizations in the typical InGaN/GaN multiple quantum well

Manuscript received April 13, 2015; revised June 04, 2015; accepted June

07, 2015. Date of publication June 11, 2015; date of current version November

12, 2015. This work is ﬁnancially supported by the National Natural Science

Foundation of China under Grant 61176085 and Grant 61377055 and by the

Department of Education of Guangdong Province, China under Grant gjhz1103.

(Corresponding author: Ting Mei and Yi An Yin.)

N. Wang, Y. A. Yin, and B. Zhao are with the Laboratory of Nanophotonic

Functional Materials and Devices, Institute of Optoelectronic Materialsand

Technology, South China Normal University, Guangzhou 510631, China

(e-mail: naiyin.wang.2015@ieee.org; yinya@scnu.edu.cn; bijunZhao@hot-

mail.com).

T. Mei is with the Key Laboratory of Space Applied Physics and Chem-

istry, Ministry of Education and Shanxi Key Laboratory of Optical Information

Technology, School of Science, Northwestern Polytechnical University, Xi’an

710072, China (e-mail: ting.mei@ieee.org).

Color versions of one or more of the ﬁgures are available online at http://

ieeexplore.ieee.org.

Digital Object Identiﬁer 10.1109/JDT.2015.2444400

(MQW) active region leads to severe band bending, which

causes quantum-conﬁned Stark effect (QCSE) and reduces

the conﬁnement capability for carriers. More speciﬁcally, the

polarization ﬁeld leads to spatial separation of electrons and

holes within quantum wells (QWs) and therefore reduces the

radiative recombination rate [10], [11]. The staggered QWs

[10], [11], semi/non-polar QWs [12], [13], and nanowire-based

structures [14] have been investigated to make electrons and

holes closer. On the other hand, the reduced conﬁnement

capability for carriers aggravates the spill-over of electrons

out of the active region [4]. In fact, the electron leakage is a

common issue in nitride-based LEDs and it is the reason why

an AlGaN electron-blocking layer (EBL) was suggested [15].

However, recent studies indicated that the EBL's capacity of

blocking electron is insufﬁcient due to the downward band

bending caused by polarization charges at GaN/AlGaN inter-

face and the utilization of that hinders the hole injection into

the active region [16]. Numerous efforts related to design of

barrier layers and EBLs in the heterostructures have been made

to alleviate the QCSE and enhance electron conﬁnement and

hole injection efﬁciency, such as adoption of AlGaInN barriers

[17], large bandgap AlInN thin barriers [18]–[20], multilayer

InGaN-GaN-InGaN barriers [21], thin AlGaN barriers [22],

the AlInN EBL [23], the AlGaN/GaN superlattice EBL [24],

etc. Furthermore, Han et al. [16] reported experimentally that

InGaN/GaN MQW LEDs without EBL have higher QE at high

current than those with EBL due to the enhanced hole injection

efﬁciency. Besides, the investigation on the characteristics

of GaN-based LEDs without EBL can also be found in [22],

[25]–[27]. Very recently, Iveland et al. indicated that Auger

process is the dominant efﬁciency droop mechanism based on a

direct observation of Auger electrons emitted from GaN-based

LEDs under electrical injection [28]. This ﬁnding is in good

agreement with previously theoretical [29] and experimental

[8] studies. Likewise, many efforts have been made to reduce

Auger effect, including study of dilute-As GaNAs alloy with

potentially lower Auger recombination rate [30], [31], local

doping modulation [32], increase of the active layer thickness

[9], and replacement of conventional GaN barriers with thin

AlGaN barriers [22], etc.

Apart from the pursuit of the progress in material epitaxy

[33], [34], the design optimization of heterostructures is an

effective approach to improve the performance of III-Nitride

LEDs [17]–[27]. In this work, GaN-based LEDs with lat-

tice-matched InGaN/AlInN/InGaN (LM-IAI) quantum well

See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.

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