XPS Studies of Sodium Compound Formation and Surface Segregation in CIGS Thin Films

    Research output: Contribution to conferencePaper


    We report X-ray Photoelectron spectroscopy (XPS) studies of device-quality CIGS thin films grown on soda-lime glass substrates. The copper atomic concentration profiles within the near-surface region indicate copper depletion, a previously reported observation attributed to the formation of the ternary defect compound Cu(In,Ga)3Se5[1]. Preferential surface segregation of sodium is also observed,as previously reported [2]. Analyses of our data indicate that the group [1]/[111] atomic concentration ratio {[Cu]+[Na]}/{[In]+[Ga]} is constant to within the accuracy of the measurement. This result is strong evidence that the composition of CIGS films grown by multisource physical vapor deposition in the presence of sodium is thermochemically constrained to lie on the pseudobinaryNa(In,Ga)Se2--Cu(In,Ga)Se2 tie-line in the ternary Na2Se--Cu2Se--(In,Ga)2Se3 composition diagram.
    Original languageAmerican English
    Number of pages4
    StatePublished - 1997
    EventTwenty Sixth IEEE Photovoltaic Specialists Conference - Anaheim, California
    Duration: 29 Sep 19973 Oct 1997


    ConferenceTwenty Sixth IEEE Photovoltaic Specialists Conference
    CityAnaheim, California

    Bibliographical note

    Work performed by University of Florida, Gainesville, Florida

    NREL Publication Number

    • NREL/CP-520-24975


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