As metal-oxide-semiconductor field-effect transistor (MOSFET) devices are shrunk to the nanometer scale, flat shallow metal/Si electrical contacts must be formed in the source/drain region. This work demonstrates a method for the formation of epitaxial NiSi2 layers by a solid-phase reaction in Ni-P(8 nm)/Si(1 0 0) samples. The results show that the sheet resistance remained low when the samples were annealed at temperatures from 400 to 700 degrees C. P atoms can be regarded as diffusion barriers against the supply of Ni to the Si substrate, which caused the formation of Si-rich silicide (NiSi2) at low temperature. Furthermore, elemental P formed a stable capping layer with O, Ni and Si during the annealing process. A uniform NiSi2 layer with an atomically flat interface was formed by annealing at 700 degrees C because of the formation of a Si-Ni-P-O capping layer and a reduction in the total interface area. (C) 2011 Elsevier B.V. All rights reserved.