Onoprienko O. Mechanisms of structure and properties formation of thin amorphous carbon based films prepared by magnetron sputtering.

The microstructure of films deposited at near room temperature is formed by small size clusters consisted of chaotically arranged and distorted rings of aromatic type. With increasing condensation temperature in the range 20-400oC more regular rings form in the films, which are arranged more ordered. An increase in substrate temperature upon condensation above 500 oC results in change in the film formation mechanism, and the nanocrystalline graphite films deposit onto substrate. Annealing in the temperature range 50-650 oC of a-C films deposited at low substrate temperature doesn't change in whole the film structure, whereas above 650 оС the graphite-like fragments form in the film structure. The hardness and elastic modulus of films decrease with increasing substrate temperature upon deposition, and don't change with annealing temperature in the range of 50-650 С. films with boron and silicon doesn't change in whole the mechanism of structure formation but slows down the process of transformation clusters into graphite-like ones in the deposition temperature range 20-400 С because of additional distortion of rings by incorporated boron and silicon atoms into them. When depositing metal-doped (Cu, Ag) films at low substrate temperature, the metal atoms are uniformly distributed within the carbon matrix and don't disturb its quasi-amorphous structure. Annealing in a vacuum of such films or deposition of the films at high (600 oC) substrate temperature results in precipitation of metal atoms in particles both in the film volume and on its surface. The process of coalescence develops within the particle ensemble located on the film surface by the surface hetero-diffusion mechanism (for Cu particles) or by the mixed mechanism of surface hetero-diffusion and simultaneous fusion of fine particles as a result of their movement as a whole onto film surface (for Ag particles).