Evolution of Electronic Properties of Cu(In,Ga)Se2 (CIGS)-Based Solar Cells During a 3-Stage Growth Process

Jehad A. AbuShama, S. Johnston, R. Ahrenkiel, R. Crandall, D. Young, R. Noufi

Research output: Contribution to conferencePaperpeer-review

2 Scopus Citations


We investigated the electronic properties of ZnO/CdS/CIGS/Mo/SLG polycrystalline thin-film solar cells with compositions ranging from Cu-rich to In(Ga)-rich by deep-level transient spectroscopy (DLTS) and capacitance-voltage (C-V) measurements. This compositional change represents the evolution of the film during growth by the 3-stage process. Two sets (four samples each) of CIGS thin films were prepared with Ga/(In+Ga) ratios of ∼0.3 (low Ga) and ∼0.6 (high Ga). The Cu/(In+Ga) ratio ranges from 1.24 (Cu-rich) to 0.88 (In(Ga)-rich). The films were treated with NaCN to remove the Cu 2-xSe phase where needed. Key results include: (1) For low-Ga devices, DLTS data show that acceptor-like traps dominate in samples where CIGS grains do not go through the Cu-rich to In(Ga)-rich transition, whereas donor-like traps dominate in In(Ga)-rich samples. Therefore, we see a clear transformation of defects from acceptor-like to donor-like traps. The activation energies of these traps range from 0.12 to 0.63 eV. We also observed that NaCN treatment eliminates a deep minority trap in the In(Ga)-rich devices, (2) For high-Ga devices, only majority-carrier traps were detected. These traps again range from shallow to deep, (3) The carrier concentration around the junction and the density of traps decrease as the CIGS becomes more In(Ga)-rich.

Original languageAmerican English
Number of pages6
StatePublished - 2003
EventCompound Semiconductor Photovoltaics: Materials Research Society Symposium - San Francisco, California
Duration: 22 Apr 200325 Apr 2003


ConferenceCompound Semiconductor Photovoltaics: Materials Research Society Symposium
CitySan Francisco, California

Bibliographical note

For preprint version including online full-text document, see; NREL/CP-520-33949.

NREL Publication Number

  • NREL/CP-520-33084


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