Direct demonstration of carrier distribution and recombination within step-bunched UV-LEDs

Houqiang Xu, Jiean Jiang, Li Chen, Jason Hoo, Long Yan, Shiping Guo, Cai Shen, Yanping Wei, Hua Shao, Zi Hui Zhang, Wei Guo, Jichun Ye

Research output: Journal PublicationArticlepeer-review

2 Citations (Scopus)

Abstract

AlGaN-based solid state UV emitters have many advantages over conventional UV sources. However, UV-LEDs still suffer from numerous challenges, including low quantum efficiency compared to their blue LED counterparts. One of the inherent reasons is a lack of carrier localization effect inside fully miscible AlGaN alloys. In the pursuit of phase separation and carrier localization inside the active region of AlGaN UV-LED, utilization of highly misoriented substrates proves to be useful, yet the carrier distribution and recombination mechanism in such structures has seldom been reported. In this paper, a UV-LED with step-bunched surface morphology was designed and fabricated, and the internal mechanism of high internal quantum efficiency was studied in detail. The correlation between microscale current distribution and surface morphology was provided, directly demonstrating that current prefers to flow through the step edges of the epitaxial layers. Experimental results were further supported by numerical simulation. It was found that efficient radiative recombination centers were formed in the inclined quantum well regions. A schematic three-dimensional energy band structure of the multiple quantum wells (MQWs) across the step was proposed and helps in further understanding the luminescence behavior of LEDs grown on misoriented substrates. Finally, a general principle to achieve carrier localization was proposed, which is valid for most ternary III-V semiconductors exhibiting phase separation.

Original languageEnglish
Pages (from-to)764-771
Number of pages8
JournalPhotonics Research
Volume9
Issue number5
DOIs
Publication statusPublished - 1 May 2021

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics

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