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Title: Depth-resolved confocal micro-Raman spectroscopy for characterizing GaN-based light emitting diode structures

In this work, we demonstrate that depth-resolved confocal micro-Raman spectroscopy can be used to characterize the active layer of GaN-based LEDs. By taking the depth compression effect due to refraction index mismatch into account, the axial profiles of Raman peak intensities from the GaN capping layer toward the sapphire substrate can correctly match the LED structural dimension and allow the identification of unique Raman feature originated from the 0.3 μm thick active layer of the studied LED. The strain variation in different sample depths can also be quantified by measuring the Raman shift of GaN A{sub 1}(LO) and E{sub 2}(high) phonon peaks. The capability of identifying the phonon structure of buried LED active layer and depth-resolving the strain distribution of LED structure makes this technique a potential optical and remote tool for in operando investigation of the electronic and structural properties of nitride-based LEDs.
Authors:
; ;  [1] ; ; ;  [2]
  1. Center for Condensed Matter Sciences, National Taiwan University, 10617 Taipei, Taiwan (China)
  2. Department of Photonics, National Chiao Tung University, 30010 Hsinchu, Taiwan (China)
Publication Date:
OSTI Identifier:
22251353
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 84; Journal Issue: 11; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; GALLIUM NITRIDES; LIGHT EMITTING DIODES; PEAKS; PHONONS; RAMAN SPECTROSCOPY; SAPPHIRE; SUBSTRATES