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Title: Cd doping at PVD-CdS/CuInGaSe 2 heterojunctions

In this paper, we report on direct evidence of Cd doping of the CuInGaSe 2 (CIGS) surface in physical vapor deposited (PVD) CdS/CIGS heterojunctions by scanning transmission electron microscopy (STEM) and related techniques. We find Cd doping of the CIGS near-surface region regardless of the presence or absence of Cu rich domains in the CdS for both zinc-blende (zb) and wurtzite (wz) CdS. However, we find that the Cd penetrates much farther into the CIGS when Cu-rich domains are present in the CdS. This suggests that Cu exchanges with Cd, increasing the concentration gradient for Cd in the CIGS and thus driving Cd into the CIGS surface. The Cd doping is clearly resolved at atomic resolution in aberration-corrected STEM-high angle annular dark field images. In zb-CdS/CIGS heterojunctions, Cd is shown to substitute for both Cu and Ga atoms, while in wz-CdS/CIGS heterojunctions Cd seems to predominantly occupy Cu sites. Finally, Cd doping in the CIGS surface layer suggests the formation of a p-n homojunction in the CIGS, which may account for the high device efficiencies, comparable to CBD-CdS/CIGS processed structures.
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [5] ;  [5] ;  [5] ;  [5] ;  [5] ;  [2] ;  [4] ;  [1]
  1. Univ. of Illinois, Urbana, IL (United States). Materials Science and Engineering
  2. Univ. of Illinois, Chicago, IL (United States). Dept. of Physics
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). National Center for Electron Microscopy
  4. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  5. MiaSole Hi-Tech, Santa Clara, CA (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 0927-0248
Grant/Contract Number:
AC52-07NA27344; AC02-05CH11231; EE0005956; DMR-0959470
Accepted Manuscript
Journal Name:
Solar Energy Materials and Solar Cells
Additional Journal Information:
Journal Volume: 164; Journal ID: ISSN 0927-0248
Research Org:
Univ. of Illinois at Urbana-Champaign, IL (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
Country of Publication:
United States
14 SOLAR ENERGY; 36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; physical vapor deposition; Cu(In; Ga)Se2 photovoltaics; Cd doping; STEM-EDS mapping; atomic resolution; p-n homojunction
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1398611; OSTI ID: 1435084