Near-surface defect distributions in Cu(In,Ga)Se2

A. Rockett, D. Liao, J. T. Heath, J. D. Cohen, Y. M. Strzhemechny, L. J. Brillson, K. Ramanathan, W. N. Shafarman

Research output: Contribution to journalConference articlepeer-review


The density and distribution of point defects in Cu(In,Ga)Se2 (CIGS) layers used for solar cell applications is critical to the resulting device performance. These devices are generally thought to be limited by recombination in the space-charge region of the collecting heterojunction. The situation is complicated by the presumed presence of an n-type surface layer on the CIGS absorber. Both the surface inversion and space-charge recombination processes are intimately tied to near-surface point defects. Here, we overview recent results on surface chemistry, transient photocapacitance spectroscopy (TPC) and depth-resolved cathodoluminescence (CL) for polycrystalline device layers from two laboratories, and single crystal epitaxial layers of three orientations. The results are combined with device modeling to provide a picture of the near-surface defect structures in these materials. The TPC results show deep defect levels ∼0.7 and 0.9 eV above the valence band. CL shows evidence of subgap radiative recombination, which increases dramatically near the sample surfaces. The results point to a near-surface Cd-containing layer, which could be responsible for the surface carrier type inversion, a near-surface region containing an elevated defect density, possibly near the valence band edge, and deep hole traps near the conduction band. Implementation of the results in a device model provides reasonable fits to the device performances.

Original languageEnglish (US)
Pages (from-to)301-306
Number of pages6
JournalThin Solid Films
StatePublished - May 1 2003
EventProceedings of Symposium B - Strasbourg, France
Duration: Jun 18 2002Jun 21 2002


  • Cathodoluminescence
  • Defects
  • Spectroscopy

ASJC Scopus subject areas

  • Surfaces, Coatings and Films
  • Condensed Matter Physics
  • Surfaces and Interfaces


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