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Title: Bandgap Engineering of Cu(In1-xGax)Se2 Absorber Layers Fabricated using CuInSe2 and CuGaSe2 Targets for One-Step Sputtering Process

Here we have demonstrated that the bandgap of Cu(In1-xGax)Se2(CIGS) absorber layers was readily controlled by using a one-step sputtering process. CIGS thin-film sample libraries with different Ga/(In + Ga) ratios were synthesized on soda-lime glass at 550 °C using a combinatorial magnetron sputtering system employing CuInSe2(CIS) and CuGaSe2(CGS) targets. Energy-dispersive X-ray fluorescence spectrometry (EDS-XRF) confirmed that the CIGS films had different Ga/(In + Ga) ratios, which were varied by the sample configuration on the substrate and ranged from 0.2 to 0.9. X-ray diffraction and Raman spectroscopy revealed that the CIGS films had a pure chalcopyrite phase without any secondary phase such as Cu-Se or ordered vacancy compound (OVC), respectively. Furthermore, we found that the optical bandgap energies of the CIGS films determined by transmittance measurements ranged from 1.07 eV to 1.53 eV as the Ga/(In + Ga) ratio increased from 0.2 to 0.9, demonstrating that the one-step sputtering process using CIS and CGS targets is another simple route to control the bandgap energy of the CIGS absorber layer.
Authors:
 [1] ;  [1] ;  [2] ;  [1]
  1. Korea Inst. of Industrial Technology, Gwangju (South Korea). Advanced Photoenergy Lab.
  2. National Renewable Energy Lab. (NREL), Golden, CO (United States). National Center for Photovoltaics
Publication Date:
OSTI Identifier:
1329089
Report Number(s):
NREL/JA-5K00-67515
Journal ID: ISSN 2159-3930
Grant/Contract Number:
AC36-08GO28308
Type:
Published Article
Journal Name:
Optical Materials Express
Additional Journal Information:
Journal Volume: 6; Journal Issue: 11; Journal ID: ISSN 2159-3930
Publisher:
Optical Society of America (OSA)
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
Language:
English
Subject:
14 SOLAR ENERGY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; bandgap; absorber layers; sputtering; thin films