Recombination by grain-boundary type in CdTe

We conducted cathodoluminescence (CL) spectrum imaging and electron backscatter diffraction on the same microscopic areas of CdTe thin films to correlate grain-boundary (GB) recombination by GB type. We examined misorientation-based GB types, including coincident site lattice (CSL) Sigma = 3, other-CSL (Sigma = 5-49), and general GBs (Sigma > 49), which make up similar to 47%-48%, similar to 6%-8%, and similar to 44%-47%, respectively, of the GB length at the film back surfaces. Statistically averaged CL total intensities were calculated for each GB type from sample sizes of >= 97 GBs per type and were compared to the average grain-interior CL intensity. We find that only similar to 16%-18% of Sigma = 3 GBs are active non-radiative recombination centers. In contrast, all other-CSL and general GBs are observed to be strong non-radiative centers and, interestingly, these GB types have about the same CL intensity. Both as-deposited and CdCl2-treated films were studied. The CdCl2 treatment reduces non-radiative recombination at both other-CSL and general GBs, but GBs are still recombination centers after the CdCl2 treatment. (C) 2015 AIP Publishing LLC.