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Mathematical and computational analysis of roughening- smoothing transitions

Visiting scientist: Prof.dr. A.A. Turkin (National Science Center "Kharkov Institute of Physics and Technology")
The present collaborative project is devoted to computer modeling of kinetics of formation and properties of nanocomposite coatings based on amorphous diamond-like carbon (DLC). Because of unique combination of mechanical, tribological and physical properties DLC-coatings are used in numerous advanced applications. We focus on an analysis of smoothening mechanism of the thin film grown with p-DC magnetron sputtering. Roughness evolution has been described by the linear stochastic equation which contains the second- and fourth-order gradient terms. It turns out that the thin film roughness can be controlled by adjusting the waveform, frequency and width of DC pulses. The transition from the roughening regime of coating growth to the smoothening one will be studied. The dramatic decrease in the surface roughness when the frequency is changed from 100 kHz to 350 kHz is explained by a strong increase of atomic diffusivity along the surface because of increase of Ar+ ion flux to the substrate.

roughening- smoothing transitions

Figure: Theoretical model of a cylindrical surface emitting particles. Label S denotes the area which is seen from a given position at substrate, i.e. which lies within the solid angle Ω.