Spectrally Filtered Cathodoluminescence Of CdTe

The imaging cathodoluminescence capability of a scanning electron microscope has been complemented by a spectral filtering technique to study the spatial origin of photoluminescence from CdTe at 77K. The intent of this work is to resolve the spatial origin of different luminescence spectral components in different regions of the crystal (e.g., midgrain, near-grain boundary, etc.). The results indicate different spatial locations for the exciton and the defect photoluminescence lines, and the association of bound exciton lines with clustered dislocations. Furthermore, the exciton line appears to originate from two different regions of the sample, which may imply bound excitons from two different binding sites. We infer from the present study that the criterion generally adopted, that a high bound exciton band intensity and a relatively low defect band intensity implies good crystal quality, may be ambiguous.