Local detection of deep carrier traps in the pn-junction of silicon solar cells

摘要

Mesa-diodes, with fully preserved solar cell structure, were fabricated at various locations of silicon solar cell. Deep level transient spectroscopy was applied for detection of carrier traps in the mesa-diodes. The parameters of the traps suggest their relation to interstitial iron and/or iron-related complexes. The density of the traps sharply falls with the distance from the pn-junction. Measurements using Schottky-diodes fabricated on top of the bulk substrate material of the cell, after etching off of the solar-cell structure, did not show the presence of the traps. The results suggest that defects, influencing the performance of solar cells, were formed inear to the pn-junctions during their fabrication. The possible origin of the defects will be discussed.