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Title: Impact of extended defects on recombination in CdTe heterostructures grown by molecular beam epitaxy

Heterostructures with CdTe and CdTe 1-xSex (x ~ 0.01) absorbers between two wider-band-gap Cd1-xMgxTe barriers (x ~ 0.25-0.3) were grown by molecular beam epitaxy to study carrier generation and recombination in bulk materials with passivated interfaces. Using a combination of confocal photoluminescence (PL), time-resolved PL, and low-temperature PL emission spectroscopy, two extended defect types were identified and the impact of these defects on charge-carrier recombination was analyzed. The dominant defects identified by confocal PL were dislocations in samples grown on (211)B CdTe substrates and crystallographic twinning-related defects in samples on (100)-oriented InSb substrates. Low-temperature PL shows that twin-related defects have a zero-phonon energy of 1.460 eV and a Huang-Rhys factor of 1.50, while dislocation-dominated samples have a 1.473-eV zero-phonon energy and a Huang-Rhys factor of 1.22. The charge carrier diffusion length near both types of defects is ~6 um, suggesting that recombination is limited by diffusion dynamics. For heterostructures with a low concentration of extended defects, the bulk lifetime was determined to be 2.2 us with an interface recombination velocity of 160 cm/s and an estimated radiative lifetime of 91 us.
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  1. Department of Physics, Colorado State University, Fort Collins, Colorado 80523, USA; National Renewable Energy Laboratory, Golden, Colorado 80401, USA
  2. National Renewable Energy Laboratory, Golden, Colorado 80401, USA
  3. Materials Science, Engineering and Commercialization Program, Texas State University, San Marcos, Texas 78666, USA
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 0003-6951
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 109; Journal Issue: 9
American Institute of Physics (AIP)
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Country of Publication:
United States
14 SOLAR ENERGY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; photoluminescence; epitaxy; II-VI semiconductors; diffusion; III-V semiconductors