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Title: Excitation mechanisms of Er optical centers in GaN epilayers

We report direct evidence of two mechanisms responsible for the excitation of optically active Er{sup 3+} ions in GaN epilayers grown by metal-organic chemical vapor deposition. These mechanisms, resonant excitation via the higher-lying inner 4f shell transitions and band-to-band excitation of the semiconductor host, lead to narrow emission lines from isolated and the defect-related Er optical centers. However, these centers have different photoluminescence spectra, local defect environments, decay dynamics, and excitation cross sections. The photoluminescence at 1.54 μm from the isolated Er optical center which can be excited by either mechanism has the same decay dynamics, but possesses a much higher excitation cross-section under band-to-band excitation. In contrast, the photoluminescence at 1.54 μm from the defect-related Er optical center can only be observed through band-to-band excitation but has the largest excitation cross-section. These results explain the difficulty in achieving gain in Er doped GaN and indicate approaches for realization of optical amplification, and possibly lasing, at room temperature.
Authors:
; ; ;  [1] ; ;  [2] ;  [3]
  1. Department of Physics, Virginia Tech, Blacksburg, Virginia 24061 (United States)
  2. Department of Electrical and Computer Engineering, Texas Tech University, Lubbock, Texas 79409 (United States)
  3. Department of Electrical and Computer Engineering, NYU Polytechnic School of Engineering, Brooklyn, New York 11201 (United States)
Publication Date:
OSTI Identifier:
22485957
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 107; Journal Issue: 17; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CHEMICAL VAPOR DEPOSITION; CROSS SECTIONS; DOPED MATERIALS; ERBIUM IONS; EXCITATION; GAIN; GALLIUM NITRIDES; ORGANOMETALLIC COMPOUNDS; SEMICONDUCTOR MATERIALS; TEMPERATURE RANGE 0273-0400 K