Effect of deposition rate and thickness on the structural and electrical properties of evaporated Ni/glass and Ni/Si(1 0 0) thin films

We have studied the effect of substrates [glass and Si(1 0 0)], of Ni thickness (tNi) and of the deposition rate [v1=13 nm/min and v2=22 nm/min] on the structural and electrical properties of evaporated Ni thin films. The Ni thickness, measured by the Rutherford backscattering (RBS) technique, ranges from 28 to 200 nm. From X-ray diffraction, it was found that all samples are polycrystalline and grow with the 〈1 1 1〉 texture. From the measure of the lattice constant, we inferred that Ni/Si samples are under a higher tensile stress than the Ni/glass ones. Moreover, in Ni/glass deposited at v1, stress is relived as tNi increases while those deposited at v2 are almost stress-free. The grain size (D) in Ni/glass with low deposition rate monotonously increases (from 54 to 140 Å) as tNi increases and are lower than those corresponding to Ni/Si. On the other hand, samples grown at v2 have a constant D, for small tNi with D in Ni/glass larger than D in Ni/Si. Ni/glass deposited at low v1 are characterized by a higher electrical resistivity (ρ) than those deposited at v2. For the latter series, ρ is practically constant with tNi but decreases with increasing grain size, indicating that diffusion at the grain boundaries rather than surface effect is responsible for the variation of ρ in this thickness range. For the Ni/glass deposed at v1 and the Ni/Si series, ρ has a more complex variation with thickness and deposition rate. These results will be discussed and correlated.