Spatially Resolved Cathodoluminescence of CdTe Thin Films and Solar Cells

    Research output: Contribution to conferencePaper


    We have investigated the spatial distribution of different transitions identified in the emission spectra of CdTe thin films and solar cells by cathodoluminescence spectroscopic imaging (CLSI). Prior to back-contact deposition, the spectra are dominated by excitons (X) and donor-to-acceptor (DAP) transitions. After contacting, Cu acceptor states are found in addition to the X and DAPrecombination processes. A very systematic behavior found in CdTe is that DAP transitions occur preferentially at grain boundaries (GBs). The distribution of these states responsible for the passivation of GBs is not affected by further processing, although additional levels participate in the recombination process. We believe that this stability is one of the reasons for the success ofthin-film CdTe solar cells. Estimates of the densities of different donors and acceptors participating in the recombination process are possible from the analysis of the evolution of the emission spectra with the excitation level. It is found that the back contact suppresses some intrinsic acceptors (associated with the A center) near the back-contact interface and, therefore, Cu acceptor statesshould be responsible for the p-typeness of the back surface more than a reduction of compensation. CLSI measurements are shown to be helpful in understanding the physics of back-contact formation.
    Original languageAmerican English
    Number of pages7
    StatePublished - 2003
    EventNational Center for Photovoltaics (NCPV) and Solar Program Review Meeting - Denver, Colorado
    Duration: 24 Mar 200326 Mar 2003


    ConferenceNational Center for Photovoltaics (NCPV) and Solar Program Review Meeting
    CityDenver, Colorado

    NREL Publication Number

    • NREL/CP-520-33591


    • cadmium telluride (CdTe) photovoltaic solar cells modules
    • cathodoluminescence (CL) spectroscopy
    • CdTe
    • CLSI
    • solar cells
    • thin films


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