FABRICATION AND CHARACTERIZATION OF FUNCTIONALLY GRADED Ni-Ti MULTILAYER THIN FILMS

A functionally graded multilayer Ni-Ti thin film was deposited on a SiO2/Si substrate by d.c.sputtering using a ramped heated Ni-Ti alloy target. The stand-alone films were crystallized at 500 degrees C in vacuum better than 10(-7) Torr. Transmission electron microscopy micrographs taken along the film cross section show two distinct regions, thin and thick, with weak R and B2 phases, respectively. The film compositions along the thickness were measured and quantified using the standard-less EELSMODEL method. The film deposited during the initial thermal ramp (thin regions) displays an average of 54 at.% Ni while the film deposited at a more elevated target temperature (thick regions) shows about 51 at.% Ni.