Sub-micrometre μ-LBIC Characterisation of Silicon Solar Cells Based on a Blue Laser Pick-up Unit

competitive and versatile optoelectronic characterisation system. A blue laser pick-up unit (LPU) is used here to achieve a highly focused laser beam with a full width half maximum as small as 250 nm on the cell’s surface. A photocurrent map is then generated with precise sample movement using a piezo stage and a pico-ammeter. We demonstrate the resolution of the device by mapping the front contact region of a PERC cell at a scanning step size of 0.5 μm. The μ-LBIC mapping allows us to identify areas of lower collection efficiency which correspond to laser doped n++ region. We show that these results from our μ-LBIC system are consistent with EBIC characterisation of similar laser doped regions. Uneven features that arise from the surface topographic effects are also visible, demonstrating the resolution capability of this technique. Despite no image optimisation or filtering, the results indicate that the lateral resolution of our μ-LBIC is comparable to that of complex confocal laser microscopes. This system can enable rapid and point-of-manufacture visualisation of micrometre level recombination inside photovoltaic devices with sub-micron resolution.