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Title: Origins of electrostatic potential wells at dislocations in polycrystalline Cu(In,Ga)Se{sub 2} thin films

Thin-film solar cells based on Cu(In,Ga)Se{sub 2} (CIGSe) reach high power-conversion efficiencies in spite of large dislocation densities of up to 10{sup 10}–10{sup 11} cm{sup −2}. The present work gives insight into the structural and compositional properties of dislocations in CIGSe thin films, which are embedded in a complete solar cell stack. These properties are related to the average electrical potential distributions obtained by means of inline electron holography. At a part of the dislocations studied, the average electrostatic potential shows local minima, all with depths of about −1.4 V. The measured average electrostatic potential distributions were modeled in order to reveal possible influences from strain fields, excess charge, and also compositional changes at the dislocation core. Cu depletion around the dislocation core, as evidenced by atom-probe tomography, explains best the measured potential wells. Their influences of the strain field around the dislocation core and of excess charge at the dislocation core are small. A structural model of dislocations in CIGSe thin films is provided which includes a Cu-depleted region around the dislocation core and gives a possible explanation for why decent photovoltaic performances are possible in the presence of rather large dislocation densities.
Authors:
 [1] ;  [2] ; ; ; ;  [3] ;  [4] ; ;  [5] ;  [6] ;  [1]
  1. Department of Semiconductor Devices, Technische Universität Berlin, Einsteinufer 19, 10587 Berlin (Germany)
  2. (Germany)
  3. Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany)
  4. Department of Microstructure Physics and Alloy Design, Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Strasse 1, 40237 Düsseldorf (Germany)
  5. Institut für Optik und Atomare Physik, Technische Universität Berlin, Sekretariat ER 1-1, Strasse des 17, Juni 135, 10623 Berlin (Germany)
  6. Institut für Experimentelle Physik, Universität Ulm, Albert-Einstein-Allee 11, 89081 Ulm (Germany)
Publication Date:
OSTI Identifier:
22277894
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 10; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; COPPER SELENIDES; DENSITY; DISLOCATIONS; ELECTRONS; ENERGY CONVERSION; GALLIUM SELENIDES; INDIUM SELENIDES; PHOTOVOLTAIC EFFECT; POLYCRYSTALS; SOLAR CELLS; STRAINS; THIN FILMS; TOMOGRAPHY