Gas-jet method of metal film deposition: direct simulation monte-carlo of He-Ag mixture flow

Nanostructured silver films were produced by the gas-jet deposition method for the temperatures of the Ag vapor source (a crucible) in the range 1200-1400K. The direct simulation Monte Carlo method was applied for modeling the silver–helium mixture flow inside the crucible with subsequent jet expansion into vacuum and detailed information on jetgasdynamics was obtained. The helium carrier gas is shown to play an important role in the deposition process by increasing both the metal atom velocity and flux onto the substrate. An optimal helium flux resulting in the maximal silver deposition rate is found. The onset of cluster formation in the Ag-He jet is determined. It is shown that for the experimental conditions silver clusters are not generated in the jet and thus the observed nanostructures are formed on the substrate surface due to diffusion and nucleation of the deposited atoms.