Characterization of Ni-Cr thin films by X-ray analysis

Abstract

The X-ray microstructures of sputtered 78at.%Ni-22at.%Cr thin films ranging from 20 to 200 nm thick were determined. Phase identification of the films indicated a disordered solid solution of chromium in nickel and that the structure of Ni-Cr is, on the atomic scale, a predominately cubic close-packed lattice mixed with a small amount of h.c.p. layers. All films showed lattice contraction normal to the film surface. The magnitude of the normal component of the macrostrain increased with the thickness of the film, at first rapidly, then leveling off when t ≥ 100 nm. The crystallite size also varied systematically with the thickness of the film: the thicker the film, the larger the crystallite size. The twin fault probabilities were found to be significantly higher (β ≥ 0.036) than those of the sputtered pure metal films. The presence of h.c.p. layers in the Ni-Cr cubic lattice contributed to a maximum value of the twin fault probability β (β = 0.076) in the film 200 nm thick. A correlation between β and the electrical resistivity ρ{variant} was observed. © 1987.