Diffusion induced atomic islands on the surface of Ni/Cu nanolayers

Abstract

Surface islands formed by grain-boundary diffusion has been studied in Ni/Cu nanolayers by in-situ low energy ion scattering spectroscopy, X-ray photoelectron spectroscopy, scanning probe microscopy and ex-situ depth profiling based on ion sputtering.In this paper a new experimental approach of measurement of grain-boundary diffusion coefficients is presented. Appearing time of copper atoms diffused through a few nanometer thick nickel layer has been detected by low energy ion scattering spectroscopy with high sensitivity. The grain-boundary diffusion coefficient can be directly calculated from this appearing time without using segregation factors in calculations. The temperature range of 2 423-463 K insures the pure C-type diffusion kinetic regime. The most important result is that surface coverage of Ni layer by Cu atoms reaches a maximum during annealing and stays constant if the annealing procedure is continued. Scanning probe microscopy measurements show a Volmer-Weber type layer growth of Cu layer on the Ni surface in the form of Cu atomic islands. Depth distribution of Cu in Ni layer has been determined by depth profile analysis.3

Characterization of nanoscale atomic motion of Si in polycrystalline Cu layer

“…The atomic flux through the copper layer continuously decreased with time and finally halted. This saturation effect of surface coverage was also experienced previously in Ni/Cu bilayer systems by Cu diffusion through a Ni layer [ 12 ], suggesting that this is a general effect in thin layers.

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“…LEIS is a surface sensitive method that enables the composition analysis of the few top-most surface atomic layers. Study of atomic diffusion by LEIS was first achieved by the authors of the paper [ 12 ]. In the present experiments, a helium ion beam of 1 keV/10 nA was used to scan sample surfaces.…”

The Role of the Material of Active Screen During the Plasma Nitriding Process

“…It can be observed that titanium was deposited from the surface to the sample, but the expected Tin was not formed near the edges because in this point the iron content was higher than in the middle; moreover, the nitrogen content was decreased too. XPs analysis was performed for a more accurate determination [19,20] which results are seen in Table 6.…”