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Title: Kinetic energy dependence of carrier diffusion in a GaAs epilayer studied by wavelength selective PL imaging

Abstract

Photoluminescence (PL) imaging has been shown to be an efficient technique for investigating carrier diffusion in semiconductors. In the past, the measurement was typically carried out by measuring at one wavelength (e.g., at the band gap) or simply the whole emission band. At room temperature in a semiconductor like GaAs, the band-to-band PL emission may occur in a spectral range over 200 meV, vastly exceeding the average thermal energy of about 26 meV. To investigate the potential dependence of the carrier diffusion on the carrier kinetic energy, we performed wavelength selective PL imaging on a GaAs double hetero-structure in a spectral range from about 70 meV above to 50 meV below the bandgap, extracting the carrier diffusion lengths at different PL wavelengths by fitting the imaging data to a theoretical model. The results clearly show that the locally generated carriers of different kinetic energies mostly diffuse together, maintaining the same thermal distribution throughout the diffusion process. Potential effects related to carrier density, self-absorption, lateral wave-guiding, and local heating are also discussed.

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
1344449
Report Number(s):
NREL/JA-5200-68008
Journal ID: ISSN 0022-2313
DOE Contract Number:
AC36-08GO28308
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Luminescence; Journal Volume: 185; Journal Issue: C
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; photoluminescence imaging; electron diffusion; thermal distribution; diffusion length; GaAs thin film

Citation Formats

Zhang, S., Su, L. Q., Kon, J., Gfroerer, T., Wanlass, M. W., and Zhang, Y. Kinetic energy dependence of carrier diffusion in a GaAs epilayer studied by wavelength selective PL imaging. United States: N. p., 2017. Web. doi:10.1016/j.jlumin.2017.01.013.
Zhang, S., Su, L. Q., Kon, J., Gfroerer, T., Wanlass, M. W., & Zhang, Y. Kinetic energy dependence of carrier diffusion in a GaAs epilayer studied by wavelength selective PL imaging. United States. doi:10.1016/j.jlumin.2017.01.013.
Zhang, S., Su, L. Q., Kon, J., Gfroerer, T., Wanlass, M. W., and Zhang, Y. Mon . "Kinetic energy dependence of carrier diffusion in a GaAs epilayer studied by wavelength selective PL imaging". United States. doi:10.1016/j.jlumin.2017.01.013.
@article{osti_1344449,
title = {Kinetic energy dependence of carrier diffusion in a GaAs epilayer studied by wavelength selective PL imaging},
author = {Zhang, S. and Su, L. Q. and Kon, J. and Gfroerer, T. and Wanlass, M. W. and Zhang, Y.},
abstractNote = {Photoluminescence (PL) imaging has been shown to be an efficient technique for investigating carrier diffusion in semiconductors. In the past, the measurement was typically carried out by measuring at one wavelength (e.g., at the band gap) or simply the whole emission band. At room temperature in a semiconductor like GaAs, the band-to-band PL emission may occur in a spectral range over 200 meV, vastly exceeding the average thermal energy of about 26 meV. To investigate the potential dependence of the carrier diffusion on the carrier kinetic energy, we performed wavelength selective PL imaging on a GaAs double hetero-structure in a spectral range from about 70 meV above to 50 meV below the bandgap, extracting the carrier diffusion lengths at different PL wavelengths by fitting the imaging data to a theoretical model. The results clearly show that the locally generated carriers of different kinetic energies mostly diffuse together, maintaining the same thermal distribution throughout the diffusion process. Potential effects related to carrier density, self-absorption, lateral wave-guiding, and local heating are also discussed.},
doi = {10.1016/j.jlumin.2017.01.013},
journal = {Journal of Luminescence},
number = C,
volume = 185,
place = {United States},
year = {Mon May 01 00:00:00 EDT 2017},
month = {Mon May 01 00:00:00 EDT 2017}
}
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