In order to study the segregation of In in polycrystalline Cu crystals the Cu was doped with a low concentration of In. Due to the very low melting point of In the electron evaporated In layer was covered with a Cu layer to prevent the melting of the In layer during the high temperature annealing process in which the Cu was diffusion doped with In. The In/Cu thin layers were characterized with X-ray diffraction (XRD) and Auger electron spectroscopy. The XRD data and the Auger depth profiles illustrated a CuxIny phase formation and segregation of In to the surface of the In/Cu layers during the heat treatments. The formation of a CuxIny phases (with a higher melting points than pure In) in the In/Cu thin layers corresponds to a change in the melting point of the system from that of pure In (156.6 degrees C) to that of the CuxIny phase with a much higher melting point. It was found that the use of phase transition in the In/Cu thin layers is a promising method to dope Cu crystals with In (approximate to 0.1 at.%) at higher annealing temperatures without melting the In or CuxIny phases. The method was further verified by doping the Cu crystals with a low concentration of In (approximate to 0.1 at.%). It was observed that the In segregated to the surface when the In doped Cu crystal was annealed. (C) 2013 Published by Elsevier B.V.