Current-voltage characteristic and sheet resistances after annealing of femtosecond laser processed sulfur emitters for silicon solar cells

摘要

The characteristics of laser doped sulfur emitters are strongly dependent on annealing processes. We show how annealing increases the efficiency of silicon solar cells with such an emitter. Sheet resistance analysis reveals that up to an annealing temperature of 400 ℃ the emitter sheet resistivity increases. A lower sulfur donor concentration is concluded, which likely occurs by means of sulfur diffusion and capturing of sulfur donors at intrinsic silicon defects. Above that temperature, the emitter sheet resistance decreases, which we find to originate from healing of laser induced structural defects involving traps within the depletion zone of the silicon pn-junction.