Modeling of grain surface modification in low pressure plasma via PIC algorithm

In recent years, material processing technologies have been remarkably improved by the ever-growing research interest and efforts in nano-science along with plasma processing techniques. In particular, low-pressure plasma has been widely employed in the coating industry due to its capability of efficiently generating active species, responsible for layer deposition, in a low temperature environment. Here, we focus our attention on the deposition process on a submicron particle submerged in a CH$_{4}$/H$_{2}$ plasma. A pre-existing PIC code, which performs the particle charging calculations, is extended to account for plasma species scattering and charge-exchange processes via a Monte Carlo Collision (MCC) method, for soft-sphere interactions between non-charged species governed by the Lennard-Jones law, and for plasma/surface and gas/surface interactions via a Monte Carlo method. The last takes advantage of the immerse boundary method which allows a localized surface reaction process and layer growth as a function of super-particle densities and sticking probability coefficients.