Cu diffusion in CdTe detected by nano-metal-plasmonic enhanced resonant Raman scattering

Copper is widely used as a p-dopant in CdTe thin film solar cells. However, Cu is not stable in CdTe and its diffusion is a big concern regarding the device stability when the CdTe solar cell is applied for long-term deployment. In this work, a new technique of nano-metal-plasmonic enhanced resonant Raman scattering (RRS) was demonstrated for quantitative study of Cu diffusion in CdTe along grain boundaries. The experimental setup was designed to directly detect Cu diffusion in CdTe. The experimental results showed that Cu diffusion in CdTe can be well described by the classical diffusion mechanism. The activation energy of Cu thermal diffusion was found to be 0.40 eV, which explains the easy diffusion of Cu in CdTe.