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The gas-jet method of diamond structures deposition with using of microwave discharge activation of precursor gases is considered. Gas-dynamic processes in gas flow in the nozzle and behind it the deposition chamber is analyzed by Direct Simulation Monte Carlo method. The peculiarities of gas mixture flow into vacuum and the chamber with background pressure 80 torr are studied. A strong effect of the distance from the nozzle exit to the substrate on the atomic hydrogen dissipation from the jet active region is shown. The essential influence of processes in the compressed layer close to substrate on the diamond deposition was discovered and described. [ABSTRACT FROM AUTHOR]

The analysis of influence of heterogeneous reactions in rarefied gas flows with dissociation and recombination is carried on for the first time, at least for hydrogen and methane flows. The flow in channels with heterogeneous reaction can be equilibrium and non-equilibrium, depending on a flow rate. Non-equilibrium effects are pronounced as a rule in the space between channel exit and substrate, where the activated gas flow to the surface of diamond deposition is formed. The gas dynamic analysis of gas jet deposition of diamond facilitates the optimization of experiments and their analysis. [ABSTRACT FROM AUTHOR]

An algorithm of the direct simulation Monte Carlo (DSMC) method of the flow of the hydrogen and methane mixture in a cylindrical channel is developed. The heterogeneous reactions on the tungsten channel surface are included into the model. Based on the elaborated algorithm, analysis of the background gas pressure effect on the flow gasdynamics and interaction of the flow particles with the substrate has been performed. The obtained results can be useful for optimization of gas-dynamic sources of activated gas in technologies of diamond synthesis. [ABSTRACT FROM AUTHOR]