Abstract The results of a study of the interaction occurring at elevated temperatures between nickel silicide contacts on n-type 〈111〉 silicon and a thin aluminum overlayer are presented. The electrical and structural characteristics of the Al-nickel silicide interaction were investigated using Schottky barrier diodes, Auger electron spectroscopy, X-ray diffraction and scanning electron microscopy. As-grown diodes were found to consist mainly of NiSi and the NiSi-Si interface exhibited a Schottky barrier energy φ Bn of 0.62 eV. Upon heat treatment the NiSi layer was transformed to the intermetallic NiAl 3, and the barrier energy for the resulting NiAl 3-Si interface was found to be 0.76 eV. The electrical characteristics of the NiAl 3 layer were stable up to 500°C and no evidence of aluminum penetration into the silicon substrate was found.