THE USE OF CATHODOLUMINESCENCE IN STUDIES OF CUXS-CDS SOLAR-CELLS

Measurements of the cathodoluminescence (CL) from CuxS-CdS cells have been made with a view to determining the value of this technique for monitoring changes (during cell fabrication or during subsequent operation) in the characteristics of the CuxS absorber layer. Two peaks in the CL spectrum (at almost-equal-to 0.8-mu-m and almost-equal-to 1.0-mu-m) were shown to be due to emission centres in the CdS layer while a third feature (at almost-equal-to 0.9-mu-m) was shown to be caused by selective absorption of the CdS emission within the CuxS layer. As the optical transmission of the CuxS layer is very dependent on the thickness and stoichiometry of the layer, the observed CL was found to be very sensitive to changes in these parameters. In addition to being a valuable non-destructive technique, the CL method was seen to be particularly sensitive to variations in the surface regions of the CuxS layer in contrast to the destructive electrochemical analysis technique which provides average parameters which tend to be dominated by the deeply penetrating inter-grain boundary protrusions.