SPATIAL ORIGIN OF VARIOUS PL LINES IN CDTE AT 77-K

We report on the spatial origin of the exciton and defect photoluminescence lines in CdTe at 77 K. A scanning electron microscope was used to obtain images of cathodoluminescence that was spectrally resolved with the help of optical filters. We observe that the exciton and the defect luminescence lines originate from different spatial locations on the sample. The exciton line itself appears to originate from two different locations, one of which is clustered dislocations. These results question the validity of the generally accepted criterion that a large ratio of exciton to defect emission in the luminescence spectrum of CdTe at 77 K implies good crystal quality.