Characterization of amorphous Ni-Si binary alloy films by flash evaporation

We previously reported on an extremely small temperature coefficient of resistivity (TCR) of thin amorphous Ni-Si film resistors fabricated by new flash evaporating method, which have a wide range of resistivity.(1) In the present paper, we describe the structural and chemical properties of these films for the purpose of clarifying the cause of resistive change of films resulting from heat treatment. X-ray diffraction patterns show that Ni-Si films with greater than 20 wt.% Si remains predominantly amorphous after heat treatment. Changes in composition and binding energy of the films resulting from heat treatment are measured by means of XPS. Electrical characteristics are also investigated as a function of Si concentration and temperature. The resistance variations resulting from heat treatment are found to originate from a structural change. The activation energy needed for this change is obtained by analyzing the extent of change during isothermal heating and found to vary from 1 eV to 2.5 eV with increasing Si content from 20 wt.% to 80 wt.%.