We have investigated the interfacial solid-phase reaction and electrical properties of Ni/Si and Ni/SiGeC systems with various Ge and C compositions. The incorporation of Ge into Si substrates raised the transition temperature from the NiSi phase to the NiSi2 phase. The incorporation of C effectively suppresses the agglomeration of NiSi and the formation of {1 1 1} facets at NiSi2/Si interface, which provides the low sheet resistance even after high temperature annealing. NiSi/Si systems show the contact resistivity as low as 10(-8) Omega cm(2) for both n(+)- and p(+)-type contacts. This is accounted by the pile-up of P at the NiSi/Si interface for n(+)-type and the low Schottky barrier height for p(+)-type contact. The pile-up of B at the NiSi/p(+)-Si0.996C0.004 interface after the annealing at 750 degreesC is also found. (C) 2003 Elsevier B.V. All rights reserved.