Fermi-level depinning and contact resistance reduction in metal/n-Ge junctions by insertion of W-encapsulating Si cluster films

We demonstrate Fermi-level depinning in metal/Ge junctions and a significant reduction of specific contact resistivity of n-Ge by inserting an ultra-thin semiconducting Si-rich W silicide film (WSin, n = 12-14) composed of W-encapsulating Si clusters. Dependence of the specific contact resistivity on the electron Schottky barrier height followed the ideal exponential relation for various contact metal species. This result indicates that the insertion of the WSin film provides a negligible contribution to contact resistivity because its tunneling resistance is very low owing to the low offset of the conduction band edge of Ge. (C) 2014 AIP Publishing LLC.