Plasma-surface interactions in the control of plasma distribution functions: $\alpha $-C:H surfaces impacted by Ar/H2 plasmas

The purpose of the study is to establish the role of surface processes in influencing and controlling characteristic plasma distributions functions during the erosion of thin $\alpha $-C:H films. The dominant effect following Ar$^{+}$ impacts on a $\alpha $-C:H film is near-surface H depletion, which results in a carbon rich near-surface-region (modified layer). The modified layer thickness increases with increasing ion energy; predicted thickness is in agreement with measurements. Energetic H$_{2}^{+}$ impacts resulted in H insertion and hydrocarbon cluster erosion. Near-surface film structure and composition result from competition between these processes. The effect of H$^{+}$ impacts and possible synergetic effect of ions, additional neutrals and VUV photons will be discussed. In addition, the species ejected into the plasma following ion and neutral impacts will alter the plasma distribution functions; these effects will be highlighted as well.