Physical characterization of residual implant damage in 4H-SiC double implanted bipolar technology

The effects of post-implant anneal conditions on the level of residual damage resulting from nitrogen and boron implants after different anneal processes are investigated using the Positron Annihilation Spectroscopy (PAS) technique. It is shown that after implantation there is a substantial defect concentration significantly below the range of the implants. However such damage is almost completely recovered after anneal in contrast with the damage close to the implant range point. Such residual damage has a strong effect on the electrical characteristics of double implanted bipolar transistors - principally though reduction in carrier mobility and lifetime. It is shown that the precise implant and anneal conditions play a strong role in the level of such damage and the subsequent electrical performance of bipolar devices.