The effect of Na on the electronic properties of Cu(In,Ga)Se2 thin films: A local-probe study

D. Azulay*, D. Abou-Ras, I. Popov, I. Balberg, O. Millo

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


We investigated the effect of Na incorporation on the electronic properties of polycrystalline CuIn0.7Ga0.3Se2 thin films using scanning tunneling microscopy and spectroscopy. The tunneling spectra indicate a reduced in-gap density of states at grain boundaries and reveal a downward band-bending in Na-rich grain boundaries with respect to the adjacent grains, in agreement with our conductive atomic force microscopy data. It thus appears that Na passivates deep-level defects at grain boundaries and induces a downward band-bending there. Moreover, we provide evidence that Na passivates mainly Cu vacancy related defects. We suggest that the grain-boundary passivation, which reduces the recombination rate of photogenerated carriers, is at least of major importance in the well known Na-induced improvement in the efficiency of the corresponding solar cells.

Original languageAmerican English
Pages (from-to)448-452
Number of pages5
JournalPhysica Status Solidi - Rapid Research Letters
Issue number6
StatePublished - 1 Jun 2016

Bibliographical note

Publisher Copyright:
© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim


  • Cu(In,Ga)Se
  • electronic properties
  • grain boundaries
  • scanning tunneling spectroscopy


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