The influence of ion-implantation on the effective Schottky barrier height of NiGe/n-Ge contacts

Comparison of current-voltage characteristics of the Se implantation NiGe/n-Ge contacts with (red) and without (blue) thermal annealing before germanidation. And (b) current-voltage characteristics of NiGe/p-Ge with (red) and without (black) Se implantation. [Display omitted] •Debate about the mechanism to modulate the electrical properties.•The influence of impurity segregation on the effective Schottky barrier height.•The influence of implantation damage on the effective Schottky barrier height.•The influence of interface passivation on the effective Schottky barrier height. The mechanism for modulating the effective Schottky barrier height of NiGe/Ge contacts by incorporating impurities is still under debate. There is a view that impurities segregated at the NiGe/Ge interface act as donors or passivators that alleviate the Fermi-level pinning effect so as to significantly affect the electrical characteristics. Our study, however, clearly demonstrates that ion implantation damage is the primary factor in causing the lowering of the effective Schottky barrier, for NiGe/n-Ge contacts doped with Se or Si, although passivation behavior is observed for P doping.