Interface reactions and Kirkendall voids in metal organic vapor-phase epitaxy grown Cu(In,Ga)Se2 thin films on GaAs

C. H. Lei, A. A. Rockett, I. M. Robertson, N. Papathanasiou, S. Siebentritt

Research output: Contribution to journalArticlepeer-review

Abstract

Cu (In1-x Gax) Se2 (CIGS) films were grown on (001) GaAs at 570 or 500 °C by means of metal organic vapor-phase epitaxy. All films were Cu-rich [Cu (In+Ga) >1] with pseudomorphic Cu2 Se second phase particles found only on the growth surface. During growth, diffusion of Ga from the substrate and vacancies generated by the formation of CIGS from Cu2 Se at the surface occurred. The diffusion processes lead to the formation of Kirkendall voids at the GaAs/CIGS interface. Transmission electron microscopy and nanoprobe energy dispersive spectroscopy were used to analyze the diffusion and void formation processes. The diffusivity of Ga in CIGS was found to be relatively low. This is postulated to be due to a comparatively low concentration of point defects in the epitaxial films. A reaction model explaining the observed profiles and voids is proposed.

Original languageEnglish (US)
Article number114915
JournalJournal of Applied Physics
Volume100
Issue number11
DOIs
StatePublished - 2006

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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