Au/Al bilayer (50-250-nm thickness) thin films were deposited by thermal evaporation on p-type silicon (10 0) substrates. The formed Au/Al/Si systems were annealed from room temperature (RT) to 400 degrees C to form AuAl/Si alloys. Two groups of AuAl alloys were analyzed. The first group was prepared as a function of the atomic concentration and the second group was prepared as a function of thickness. The morphology and crystalline structure of the alloys were analyzed by AFM and X-ray diffraction techniques, respectively. The electrical resistivities of the AuAl alloys were measured by the four-probe technique. The first group of thin AuAl alloys presented segregations as a consequence of the annealing treatment and the atomic concentration; meanwhile, the electrical resistivity showed abrupt changes as a consequence of changing the atomic concentration. In the second group a monotonically increment in the grain size was found meanwhile for thickness below 100 nm the electrical resistivity presented important differences as compared with the before annealing process. (C) 2009 Elsevier B.V. All rights reserved.