Electrical contacts of NiSi0.82Ge0.18 to P+-Si0.82Ge0.18 were fabricated and characterised. Lateral growth of the NiSi0.82Ge0.18 under SiO2 isolation was observed. A three-dimensional model was employed to extract the contact resistivity by considering both the lateral growth and the presence of a recessed NiSi0.82Ge0.18 step into the Si0.82Ge0.18. The contact resistivity extracted was 5.0 x 10(-8) and 1.4 x 10(-7) Omega cm(2) for small contacts of circular geometry and large contacts of square shape, respectively. Possible causes responsible for this 3-fold difference in contact resistivity were discussed. An underestimate of the contact resistivity by 35% was found if a two-dimensional model was used without taking into account the complex interface morphology. (c) 2005 Elsevier B.V All rights reserved.