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Title: Influence of different sulfur to selenium ratios on the structural and electronic properties of Cu(In,Ga)(S,Se){sub 2} thin films and solar cells formed by the stacked elemental layer process

In this study, we investigate the effect of different elemental selenium to elemental sulfur ratios on the chalcopyrite phase formation in Cu(In,Ga)(S,Se){sub 2} thin films. The films are formed by the stacked elemental layer process. The structural and electronic properties of the thin films and solar cells are analyzed by means of scanning electron microscopy, glow discharge optical emission spectrometry, X-ray diffraction, X-ray fluorescence, Raman spectroscopy, spectral photoluminescence as well as current-voltage, and quantum efficiency measurements. The influence of different S/(S+Se) ratios on the anion incorporation and on the Ga/In distribution is investigated. We find a homogenous sulfur concentration profile inside the film from the top surface to the bottom. External quantum efficiency measurements show that the band edge of the solar cell device is shifted to shorter wavelength, which enhances the open-circuit voltages. The relative increase of the open-circuit voltage with S/(S+Se) ratio is lower than expected from the band gap energy trend, which is attributed to the presence of S-induced defects. We also observe a linear decrease of the short-circuit current density with increasing S/(S+Se) ratio which can be explained by a reduced absorption. Above a critical S/(S+Se) ratio of around 0.61, the fill factor drops drastically, whichmore » is accompanied by a strong series resistance increase which may be attributed to changes in the back contact or p-n junction properties.« less
Authors:
 [1] ;  [2] ; ; ; ;  [1] ;  [3] ;  [4]
  1. Robert Bosch GmbH, Corporate Research and Advance Engineering, Advanced Functional Materials and Microsystems, D-70839 Gerlingen (Germany)
  2. (Germany)
  3. Bosch Solar CISTech GmbH, D-14772 Brandenburg (Germany)
  4. Institute of Micro- and Nanomaterials, University of Ulm, D-89081 Ulm (Germany)
Publication Date:
OSTI Identifier:
22308217
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 17; 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; ABSORPTION; CONCENTRATION RATIO; COPPER COMPOUNDS; EMISSION SPECTROSCOPY; FILL FACTORS; FLUORESCENCE; GALLIUM COMPOUNDS; INDIUM COMPOUNDS; PHOTOLUMINESCENCE; P-N JUNCTIONS; QUANTUM EFFICIENCY; RAMAN SPECTROSCOPY; SCANNING ELECTRON MICROSCOPY; SELENIUM COMPOUNDS; SOLAR CELLS; SULFUR COMPOUNDS; THIN FILMS; X RADIATION; X-RAY DIFFRACTION