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Title: Optical and structural study of GaN nanowires grown by catalyst-free molecular beam epitaxy. II. Sub-band-gap luminescence and electron irradiation effects

Abstract

GaN nanowires with diameters of 50-250 nm, grown by catalyst-free molecular beam epitaxy, were characterized by photoluminescence (PL) and cathodoluminescence (CL) spectroscopy at temperatures from 3 to 297 K. Both as-grown samples and dispersions of the nanowires onto other substrates were examined. The properties of the near-band-edge PL and CL spectra were discussed in Part I of this study by [Robins et al. [L. H. Robins, K. A. Bertness, J. M. Barker, N. A. Sanford, and J. B. Schlager, J. Appl. Phys. 101,113505 (2007)]. Spectral features below the band gap, and the effect of extended electron irradiation on the CL, are discussed in Part II. The observed sub-band-gap PL and CL peaks are identified as phonon replicas of the free-exciton transitions, or excitons bound to structural defects or surface states. The defect-related peaks in the nanowires are correlated with luminescence lines previously reported in GaN films, denoted the Y lines [M. A. Reshchikov and H. Morkoc, J. Appl. Phys. 97, 061301 (2005)]. The CL was partially quenched by electron beam irradiation for an extended time; the quenching was stronger for the free and shallow-donor-bound exciton peaks than for the defect-related peaks. The quenching appeared to saturate at high irradiation dosemore » (with final intensity {approx_equal}30% of initial intensity) and was reversible on thermal cycling to room temperature. The electron irradiation-induced quenching of the CL is ascribed to charge injection and trapping phenomena.« less

Authors:
; ; ; ;  [1];  [2]
  1. National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
20979411
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 101; Journal Issue: 11; Other Information: DOI: 10.1063/1.2736266; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ABSORPTION SPECTRA; CATHODOLUMINESCENCE; CRYSTAL DEFECTS; CRYSTAL GROWTH; ELECTRON BEAMS; ENERGY GAP; EXCITONS; GALLIUM NITRIDES; IRRADIATION; MOLECULAR BEAM EPITAXY; PHONONS; PHOTOLUMINESCENCE; QUANTUM WIRES; QUENCHING; RADIATION DOSES; SEMICONDUCTOR MATERIALS; TEMPERATURE RANGE 0273-0400 K; THERMAL CYCLING; THIN FILMS

Citation Formats

Robins, Lawrence H., Bertness, Kris A., Barker, Joy M., Sanford, Norman A., Schlager, John B., and National Institute of Standards and Technology, Boulder, Colorado 80305. Optical and structural study of GaN nanowires grown by catalyst-free molecular beam epitaxy. II. Sub-band-gap luminescence and electron irradiation effects. United States: N. p., 2007. Web. doi:10.1063/1.2736266.
Robins, Lawrence H., Bertness, Kris A., Barker, Joy M., Sanford, Norman A., Schlager, John B., & National Institute of Standards and Technology, Boulder, Colorado 80305. Optical and structural study of GaN nanowires grown by catalyst-free molecular beam epitaxy. II. Sub-band-gap luminescence and electron irradiation effects. United States. doi:10.1063/1.2736266.
Robins, Lawrence H., Bertness, Kris A., Barker, Joy M., Sanford, Norman A., Schlager, John B., and National Institute of Standards and Technology, Boulder, Colorado 80305. 2007. "Optical and structural study of GaN nanowires grown by catalyst-free molecular beam epitaxy. II. Sub-band-gap luminescence and electron irradiation effects". United States. doi:10.1063/1.2736266.
@article{osti_20979411,
title = {Optical and structural study of GaN nanowires grown by catalyst-free molecular beam epitaxy. II. Sub-band-gap luminescence and electron irradiation effects},
author = {Robins, Lawrence H. and Bertness, Kris A. and Barker, Joy M. and Sanford, Norman A. and Schlager, John B. and National Institute of Standards and Technology, Boulder, Colorado 80305},
abstractNote = {GaN nanowires with diameters of 50-250 nm, grown by catalyst-free molecular beam epitaxy, were characterized by photoluminescence (PL) and cathodoluminescence (CL) spectroscopy at temperatures from 3 to 297 K. Both as-grown samples and dispersions of the nanowires onto other substrates were examined. The properties of the near-band-edge PL and CL spectra were discussed in Part I of this study by [Robins et al. [L. H. Robins, K. A. Bertness, J. M. Barker, N. A. Sanford, and J. B. Schlager, J. Appl. Phys. 101,113505 (2007)]. Spectral features below the band gap, and the effect of extended electron irradiation on the CL, are discussed in Part II. The observed sub-band-gap PL and CL peaks are identified as phonon replicas of the free-exciton transitions, or excitons bound to structural defects or surface states. The defect-related peaks in the nanowires are correlated with luminescence lines previously reported in GaN films, denoted the Y lines [M. A. Reshchikov and H. Morkoc, J. Appl. Phys. 97, 061301 (2005)]. The CL was partially quenched by electron beam irradiation for an extended time; the quenching was stronger for the free and shallow-donor-bound exciton peaks than for the defect-related peaks. The quenching appeared to saturate at high irradiation dose (with final intensity {approx_equal}30% of initial intensity) and was reversible on thermal cycling to room temperature. The electron irradiation-induced quenching of the CL is ascribed to charge injection and trapping phenomena.},
doi = {10.1063/1.2736266},
journal = {Journal of Applied Physics},
number = 11,
volume = 101,
place = {United States},
year = 2007,
month = 6
}
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