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Title: S–Te Interdiffusion within Grains and Grain Boundaries in CdTe Solar Cells

At the CdTe/CdS interface, a significant Te-S interdiffusion has been found a few nanometers into the grain interiors with scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS). S substitution at Te sites has been directly resolved in CdTe with STEM Z-contrast images. Moreover, when enough S substitutes for Te, a structural transformation from zinc-blende to wurtzite has been observed. Cl segregation has also been found at the interface. STEM electron-beam-induced current (EBIC) shows that the p-n junction occurs a few nm into the CdTe grains, which is consistent with the S diffusion range we observe. The shift of the p-n junction suggests a buried homo-junction which would help reduce non-radiative recombination at the junction. Meanwhile, long-range S diffusion in CdTe grain boundaries (GBs) has been detected, as well as Te and Cl diffusion in CdS GBs.
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [3] ;  [7]
  1. Vanderbilt Univ., Nashville, TN (United States). Dept. of Chemistry
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering
  3. Univ. of Toledo, OH (United States). Dept. of Physics and Astronomy
  4. Univ. of Oxford (United Kingdom). Dept. of Materials
  5. Univ. of Manchester (United Kingdom). School of Materials
  6. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  7. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering
Publication Date:
OSTI Identifier:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
IEEE Journal of Photovoltaics
Additional Journal Information:
Journal Volume: 4; Journal Issue: 6; Journal ID: ISSN 2156-3381
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); UK Engineering and Physical Sciences Research Council
Country of Publication:
United States
36 MATERIALS SCIENCE; 14 SOLAR ENERGY CdTe; interface scanning transmission electron; microscopy; thin-film photovoltaic