Schottky barriers atNiSi2/Si(111) interfaces

The electronic structures of the two types of ${\mathrm{NiSi}}_2$/Si(111) interface were studied within the local-density approximation using the linear muffin-tin orbitals method in the atomic-sphere approximation. Calculations were done for four supercell sizes. The largest supercell contained 12 ${\mathrm{Si}}_2$ layers and 11 ${\mathrm{NiSi}}_2$ layers. With each large supercell, the difference between the Schottky-barrier heights (SBH’s) of the two types of interface was consistent with experimental values. However, SBH’s depend on the supercell size, although larger supercells have enough layers to screen the interface disturbance. Why SBH’s depend on the cell size is investigated.