Near-field transport imaging application of photovoltaic materials
We applied a novel analytical technique-near-field transport imaging (TI)-to photovoltaic materials for charge-carrier transport mapping in nanometer-scale. We measured the diffusion length of a well-controlled gallium arsenide (GaAs) thin-film samples and it agrees well with the results calculated by time-resolved photoluminescence. We report for the first time on TI experiments on thin-film cadmium telluride, including the effective carrier diffusion length, as well as the first near-field imaging of the effect of a single small defect on carrier transport and recombination in a GaAs sample. Furthermore, by changing the scanning setup, we were able to do near-field cathodoluminescence (CL), and correlated the results with standard CL results. The TI technique shows great potential for high spatial resolution mapping transport properties in solar cell materials.