中国物理B ›› 2016, Vol. 25 ›› Issue (11): 117102-117102.doi: 10.1088/1674-1056/25/11/117102

• CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES • 上一篇    下一篇

Current spreading in GaN-based light-emitting diodes

Qiang Li(李强), Yufeng Li(李虞锋), Minyan Zhang(张敏妍), Wen Ding(丁文), Feng Yun(云峰)   

  1. 1 Key Laboratory of Physical Electronics and Devices of Ministry of Education and Shaanxi Provincial Key Laboratory of Photonics & Information Technology, Xi'an Jiaotong University, Xi'an 710049, China;
    2 Solid-State Lighting Engineering Research Center, Xi'an Jiaotong University, Xi'an 710049, China
  • 收稿日期:2016-01-30 修回日期:2016-07-27 出版日期:2016-11-05 发布日期:2016-11-05
  • 通讯作者: Feng Yun E-mail:fyun2010@mail.xjtu.edu.cn
  • 基金资助:
    Project supported by the National High Technology Research and Development Program of China (Grant No. 2014AA032608), the National Natural Science Foundation of China (Grant No. 61404101), and the China Postdoctoral Science Foundation (Grant No. 2014M562415).

Current spreading in GaN-based light-emitting diodes

Qiang Li(李强)1,2, Yufeng Li(李虞锋)1,2, Minyan Zhang(张敏妍)2, Wen Ding(丁文)1,2, Feng Yun(云峰)1,2   

  1. 1 Key Laboratory of Physical Electronics and Devices of Ministry of Education and Shaanxi Provincial Key Laboratory of Photonics & Information Technology, Xi'an Jiaotong University, Xi'an 710049, China;
    2 Solid-State Lighting Engineering Research Center, Xi'an Jiaotong University, Xi'an 710049, China
  • Received:2016-01-30 Revised:2016-07-27 Online:2016-11-05 Published:2016-11-05
  • Contact: Feng Yun E-mail:fyun2010@mail.xjtu.edu.cn
  • Supported by:
    Project supported by the National High Technology Research and Development Program of China (Grant No. 2014AA032608), the National Natural Science Foundation of China (Grant No. 61404101), and the China Postdoctoral Science Foundation (Grant No. 2014M562415).

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摘要： We have investigated the factors affecting the current spreading length (CSL) in GaN-based light-emitting diodes (LEDs) by deriving theoretical expressions and performing simulations with APSYS. For mesa-structure LEDs, the effects of both indium tin oxide (ITO) and n-GaN are taken into account for the first time, and a new Q factor is introduced to explain the effects of different current flow paths on the CSL. The calculations and simulations show that the CSL can be enhanced by increasing the thickness of the ITO layer and resistivity of the n-GaN layer, or by reducing the resistivity of the ITO layer and thickness of the n-GaN layer. The results provide theoretical support for calculating the CSL clearly and directly. For vertical-structure LEDs, the effects of resistivity and thickness of the CSL on the internal quantum efficiency (IQE) have been analyzed. The theoretical expression relating current density and the parameters (resistivity and thickness) of the CSL is obtained, and the results are then verified by simulation. The IQE under different current injection conditions is discussed. The effects of CSL resistivity play a key role at high current injection, and there is an optimal thickness for the largest IQE only at a low current injection.

关键词: current spreading length, light-emitting diodes, indium tin oxide, quantum efficiency

Abstract: We have investigated the factors affecting the current spreading length (CSL) in GaN-based light-emitting diodes (LEDs) by deriving theoretical expressions and performing simulations with APSYS. For mesa-structure LEDs, the effects of both indium tin oxide (ITO) and n-GaN are taken into account for the first time, and a new Q factor is introduced to explain the effects of different current flow paths on the CSL. The calculations and simulations show that the CSL can be enhanced by increasing the thickness of the ITO layer and resistivity of the n-GaN layer, or by reducing the resistivity of the ITO layer and thickness of the n-GaN layer. The results provide theoretical support for calculating the CSL clearly and directly. For vertical-structure LEDs, the effects of resistivity and thickness of the CSL on the internal quantum efficiency (IQE) have been analyzed. The theoretical expression relating current density and the parameters (resistivity and thickness) of the CSL is obtained, and the results are then verified by simulation. The IQE under different current injection conditions is discussed. The effects of CSL resistivity play a key role at high current injection, and there is an optimal thickness for the largest IQE only at a low current injection.

Key words: current spreading length, light-emitting diodes, indium tin oxide, quantum efficiency

中图分类号:  (Methods of electronic structure calculations)

  • 71.15.-m
73.61.Ey (III-V semiconductors) 71.55.Eq (III-V semiconductors)