Specific contact resistivity of n-type Si and Ge M-S and M-I-S contacts

We have theoretically investigated the specific contact resistivity of n-type Si and Ge metal-insulator-semiconductor contacts with various insulating oxides. We have found a significant reduction of the contact resistivity for both Si and Ge with an insertion of insulators at low and moderate donor doping levels. However, at the higher doping levels (>10²⁰ cm^u-3), the reduction of the contact resistivity is negligible and the contact resistivity increases as the insulator thickness increase. Thus, we have shown that the lowest possible contact resistivity can be achieved with the metal-semiconductor contact with highest possible activated doping density.