The I-V/C-V characteristics of Ni silicide/n-Si(1 0 0) contacts, which were formed at various annealing temperatures from 350 to 800 degreesC, were studied in the temperature range from 100 K up to room temperature. The experimental I-V data of the low temperature annealed diodes obey the traditional thermionic emission (TE) model quite well, and the barrier heights are deduced to be approximately 0.62 eV for Ni2Si/Si and 0.67 eV for NiSi/Si diodes respectively. For high temperature annealed samples, the current in the low bias region exceeds significantly that predicted by the TE model. The phenomenon can be attributed to patches with low barrier height embedded in the contact. Using Tung's pinch-off model, the patch's properties (the patch size, the number of patches and the local series resistance) are deduced by the deconvolution of the experimental I-V data. Both the patch size and its density increase significantly with increasing the annealing temperature. In other words, high temperature anneal degenerates the Ni silicide/Si Schottky contact. (C) 2003 Elsevier Ltd. All rights reserved.