Study of the excitation power dependent internal quantum efficiency in InGaN/GaN LEDs grown on patterned sapphire substrate

Ya Ju Lee, Ching Hua Chiu, Chih Chun Ke, Po Chun Lin, Tien Chang Lu, Hao Chung Kuo, Shing Chung Wang

Research output: Contribution to journalArticle

100 Citations (Scopus)

Abstract

The mechanisms of the excitation power dependent internal quantum efficiency in InGaN/GaN multiple quantum wells (MQWs) LEDs grown on the planar and the patterned sapphire substrates (PSS) at temperature of 15 and 300 K were investigated. From observation the tendency of emission peak energy and carrier lifetime variation in MQWs with different excitation power for both LED samples, we conclude the internal quantum efficiency would increase as coulomb screening effect dominates at lower carrier injection stage and decrease due to the band-filling effect at higher density stage. At room temperature, the majority of the initial injected carriers would be first consumed by the thermal activated nonradiative centers that hinder the further achievement of high-efficiency LED devices. Experimentally, the internal quantum efficiency of the LED grown on the PSS is $70% and that of the LED grown on the planar sapphire substrate is $62%. For the LED grown on the PSS, the observed higher internal quantum efficiency is due to the larger activation energy Therefore, the reduction of dislocation defects and the prevention of injected carriers escaping from extended states would be a promising prospective for InGaN/GaN MQWs LEDs to achieve high internal quantum efficiency.

Original languageEnglish
Article number4815458
Pages (from-to)1137-1143
Number of pages7
JournalIEEE Journal on Selected Topics in Quantum Electronics
Volume15
Issue number4
DOIs
Publication statusPublished - 2009 Apr 21

Keywords

  • GaN
  • Internal quantum efficiency
  • LEDs

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Electrical and Electronic Engineering

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