Electrical Conductivity of Thin Films of CoNi and FeNi Alloys

This paper presents the results of the study of the electrical conductivity of structurally continuous thin films of CoNi and FeNi alloys in a wide range of thicknesses and concentrations of components. Alloy films with a thickness of 10-200 nm were obtained by condensation of evaporated initial massive binary alloys of CoNi and FeNi in a vacuum of 10 – 4 Pa. CoNi alloys were evaporated by electron beam method using an electron diode gun with a condensation rate of 0.5-1.5 nm/s. The purity of the initial metals Co and Ni was not less than 99.9%. The concentrations of components of CoNi alloy films varied in a wide range. FeNi alloy films were obtained as a result of evaporation with a 50N permafrost. Thermostabilizing of the electrophysical properties of alloy films was carried out during three heating-cooling cycles in the temperature range of 300-700 K. The dependences of the specific electrical resistance on the temperature of alloy films for the second and subsequent heating-cooling cycles practically coincide, which indicates complete stabilization of the properties of film samples after the second annealing cycle. An irreversible decrease in electrical resistance after heat treatment was experimentally revealed, which indicates ordering of the material structure. It was shown that the nature of changes in electrical resistance depends on both the thickness of the films and the ratio of components in the alloys. To interpret the obtained results, the Wend model of healing of defects in the crystalline structure of films was used, which allows us to explain the decrease in electrical resistance due to a decrease in the concentration of defects and an improvement in structural ordering. Based on this model, the spectra of defects in the crystalline structure in CoNi and FeNi alloy films were calculated.