Recrystallization of PVD CdTe thin films induced by CdCl2 treatment - A comparison between vapor and solution processes

The untreated physical-vapor-deposited CdTe films had small grains, with ≪111≫ texture, and a large concentration of deep levels. For CdCl2 treatments at moderate temperature/time, there was partial recrystallization, and a moderate decrease in the concentration of deep levels. For the optimal treatment conditions, there was complete recrystallization and grain growth, and further decrease in stress. Electron backscatter diffraction showed that these films had a mixture of small and large grains, many larger than 30 μm. The larger grains had ≪111≫ orientation, whereas the smaller grains were randomly oriented, which provided insight on the grain-growth mechanism after recrystallization. There was a significant increase in the cathodoluminescence signal, indicating a decrease in the concentration of deep levels. When performed at the same conditions, the CdCl2 vapor treatment is more effective in the recrystallization and grain-growth processes than the solution CdCl2 treatment. All the films had a large concentration of twin boundaries.