Chalcopyrite/Si heterojunctions for photovoltaic applications

O. Akpa, S. Shoieb, T. Thompson, T. Isaacs-Smith, P. Anderson, S. Seraphin, K. Das

Research output: Contribution to journalArticle

4 Scopus citations

Abstract

Films of CuInSe 2 (CIS) and CuGaSe 2 (CGS) were deposited on (100) Si by radiofrequency (RF) magnetron sputtering from stoichiometric CIS and CGS targets. Rutherford backscattering (RBS) analysis yielded a composition of Cu 0.8In 1.1Se 1.9 for CuInSe 2, which indicates that these films were Cu and Se poor. A composition of Cu 0.3Ga 1.5Se 2.0 for CuGaSe 2 shows Ga-rich and Cu-poor layers. Transmission electron microscopy (TEM) of cross-sectional samples established that the films were polycrystalline in nature and free of pinhole defects that normally short-circuit devices fabricated on glass with submicron absorber layers. From the electron and x-ray diffraction patterns, tetragonal chalcopyrite phases of the material were identified. Circular diodes, with a diameter between 100 μm and 400 μm, were fabricated on the grown films with a common Au back-contact. Diodes on both CIS and CGS films exhibited rectifying characteristics. From the polarity corresponding to the high and low currents, it was inferred that the grown films were p-type. These diodes exhibited photovoltaic response, and the forward-bias current increased by as much as two orders of magnitude when illuminated by a 75-W halogen lamp. The open-circuit voltages (V OC) for these devices are expected to approach the turn-on voltage of the diodes, 0.5 V and 0.7 V, for the CGS/Si and the CIS/Si heterojunctions, respectively. Shunting caused by degenerate phases present in the CGS film is believed to have resulted in the observed lower turn-on voltage for the CGS/n-Si heterojunction diode.

Original languageEnglish (US)
Pages (from-to)2462-2466
Number of pages5
JournalJournal of Electronic Materials
Volume39
Issue number11
DOIs
StatePublished - Nov 1 2010

Keywords

  • Chalcopyrite
  • CuGaSe
  • CuInSe
  • Heterojunction
  • Photovoltaic
  • Sputtering

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering
  • Materials Chemistry

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  • Cite this

    Akpa, O., Shoieb, S., Thompson, T., Isaacs-Smith, T., Anderson, P., Seraphin, S., & Das, K. (2010). Chalcopyrite/Si heterojunctions for photovoltaic applications. Journal of Electronic Materials, 39(11), 2462-2466. https://doi.org/10.1007/s11664-010-1365-3