Electrical characteristics of hydrogen implanted silicon Schottky diodes having large difference in metal work function

Hydrogen ion implantation was carried out on Schottky diodes having large difference in metal work function, Ti/p-Si and PtSi/p-Si diodes. Current-voltage (I-V) measurements showed that, following ion implantation, Ti/p-Si diodes exhibited rectifying characteristics; in contrast, no significant rectifying behavior was observed in the PtSi/p-Si diodes. These results showed a dependence of the implantation effects upon metal overlayer work functions. Consequently, the observations did not seem to indicate the occurrence of Fermi level pinning due to a highly damaged near-surface region after ion implantation, as previously suggested. Capacitance-voltage (C-V) measurements revealed a decrease in the diode capacitances along with a significant reduction of acceptor concentration following the implantation. In general, the results suggest that ion implantation alters the electrical characteristic of the diodes mainly by creating defects in the semiconductor depletion region. All such defects act as recombination centers giving rise to a deviation of the electrical characteristics from the normal behavior. They do not play a role in producing a Fermi level pinning.