Decoupling grain-boundary, grain-interior, and surface recombination with cathodoluminescence

In this work, we combine quantitative cathodoluminescence (CL) with time-resolved photoluminescence (TRPL) and numerical simulations to determine grain-boundary, grain-interior, and surface recombination parameters in standard $\mathbf{CdTe}$ thin films. CL intensities from thousands of grains are analyzed to accumulate statistics and chart variations with grain size. Grain-boundary contrast results for small grains indicate that the grain-boundary recombination velocity, $s_{GB}$, decreases significantly with $\mathrm{CdC}1_{2}$ treatment, but $s_{GB}$ is increased by subsequent Cu-diffusion. Furthermore, within a given sample, data suggests that $s_{GB}$ is nearly independent of grain size. The back-surface recombination velocity, S, is extracted from TRPL measurements incident on the back surface, and CL profiles are simulated to determine the grain-interior lifetime, $\tau_{G1}$, Finally, CL intensity vs. grain size relationships are simulated to check for self-consistency of the $s_{GB}, s$, and $\tau_{G1}$ values.