High resolution saturation current density imaging at grain boundaries by lock-in thermography

The electronic properties of multicrystalline solar silicon materials are dominated by low-lifetime defect regions containing recombination-active grain boundaries and dislocations. Besides reducing the carrier collection probability, these regions increase the dark saturation current density J01, which governs the open circuit voltage. By applying lock-in thermography with spatial deconvolution it is shown that the dominant contribution to J01 comes from recombination-active grain boundaries and to a lower degree from intra-grain defects like dislocations.