Strain Relaxation Effect on the Peak Wavelength of Blue InGaN/GaN Multi-Quantum Well Micro-LEDs

Chaoqiang Zhang, Ke Gao, Fei Wang, Zhiming Chen, Philip Shields, Sean Lee, Yanqin Wang, Dongyan Zhang, Hongwei Liu, Pingjuan Niu

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13 Citations (SciVal)

Abstract

In this paper, the edge strain relaxation of InGaN/GaN MQW micro-pillars is studied. Micro-pillar arrays with a diameter of 3–20 μm were prepared on a blue GaN LED wafer by inductively coupled plasma (ICP) etching. The peak wavelength shift caused by edge strain relaxation was tested using micro-LED pillar array room temperature photoluminescence (PL) spectrum measurements. The results show that there is a nearly 3 nm peak wavelength shift between the micro-pillar arrays, caused by a high range of the strain relaxation region in the small size LED pillar. Furthermore, a 19 μm micro-LED pillar’s Raman spectrum was employed to observe the pillar strain relaxation. It was found that the Raman E2H mode at the edge of the micro-LED pillar moved to high frequency, which verified an edge strain relaxation of = 0.1%. Then, the exact strain and peak wavelength distribution of the InGaN quantum wells were simulated by the finite element method, which provides effective verification of our PL and Raman strain relaxation analysis. The results and methods in this paper provide good references for the design and analysis of small-size micro-LED devices.
Original languageEnglish
Article number7431
JournalApplied Sciences
Volume12
Issue number15
DOIs
Publication statusPublished - 24 Jul 2022

Bibliographical note

Funding Information:
This research was funded by the Tianjin Municipal Science and Technology Bureau, Grant 18JCYBJC85400, Grant 18ZXCLGX00090, Grant 20JCQNJC00180 and Grant 19JCTPJC48000; in part by the China Scholarship Council (CSC), Grant 201809345004; and in part by the Tianjin Key Laboratory of Optoelectronic Detection Technology and System under Grant TD13-5035 and Grant 2017ZD06.

Keywords

  • InGaN/GaN multiple quantum well (MQW)
  • Raman shift
  • micro-LED arrays
  • photoluminescence (PL)
  • strain relaxation

ASJC Scopus subject areas

  • General Materials Science
  • Instrumentation
  • General Engineering
  • Process Chemistry and Technology
  • Computer Science Applications
  • Fluid Flow and Transfer Processes

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