ELECTRICAL-PROPERTIES OF DISLOCATIONS IN PLASTICALLY DEFORMED FLOAT-ZONE SILICON

The electrical activity of dislocations created in plastically deformed Float Zone (FZ) silicon wafers have been investigated by means of Deep Levels Transient Spectroscopy (DLTS), of Light Beam Induced Current (LBIC) mappings and of I-V Curves. It was found that these dislocations recombine minority carriers due to the generation of deep traps associated to dangling bonds and the aggregation of point defects. Dislocations induce also a soft breakdown in reverse biased aluminium silicon diodes by means of microplasmas. Annealing of the deformed wafers at 1000 degrees C for 1 hour reduces drastically the deep trap density and suppresses the soft breakdown in Al-Si diodes, probably due to the modification of the point defect atmosphere and the reconstruction of the dislocation core.