Estimation of Requirements for the Formation of Nanocrystalline Diamond Driven by Electron Beam Ablation

Conditions for the formation of thin films of nanocrystalline diamond by electron-beam ablation of a graphite target are studied. The analysis is based on the predictions of the analytical solutions of two models describing the expansion of the plasma plume into a background gas and toward a substrate. The models allow the calculation of the pressure and temperature of ablated nanoparticles upon impact with the substrate where the film is deposited. The calculation data are reported on the phase diagram of carbon and are used to assess conditions under which the diamond phase is likely to form on the substrate. The results show that decreasing gas pressure and target to substrate distance, over the practical range of accelerating voltage, is conducive to diamond formation.