The iridium-silicide (IrSi) polycrystalline nanometer thin films have been deposited on p-Si(100) substrates by a pulsed laser deposition at a room temperature and followed by in situ annealing at 300, 500, and 800 degrees C, respectively. The Schottky barrier heights (SBHs) of 0.185, 0.178 and 0.177 eV have been determined by I-V measurements. The SBHs decrease with an increase of annealing temperature due to the nanometer size effect of the IrSi polycrystalline. The measured maximum responsivity of the sample is up to 10 mA/W. (c) 2005 Elsevier B.V. All rights reserved.