Finally, the self-limiting deposition found (Fig. ) suggests a level of control over the surface chemistry, which we will here elaborate on. The substantial redeposition suggested shows that this control is limited during the plasma step of the deposition cycle. It should be noted that while the plasma is only used as a source of electrons, it will lead to both plasma volume reactions, as seen from OES (Fig. ) and plasma induced surface chemical reactions. One possible consequence thereof is the emission of secondary electrons from the surface due (primary) electron bombardment. Such electrons could potentially contribute to surface chemical reactions. The energy threshold for secondary electron emission generally falls in the range of 50-100 eV, with exact values depending on the material. There is usually a maximum in the secondary electron yield (SEY) that occurs when the incident electron has an energy above a certain threshold, and this is typically in the range of 100-300 eV. The SEY begins to decrease as the incident electron's energy increases further. From our previous study on the plasma physics of our hollow cathode plasma we expect to have a potential difference between the plasma electrons and the substrate of around 30 V. We thus assume that our (primary) plasma electrons therefore do not have sufficient energy to liberate secondary electrons from the surface. Furthermore, it is highly unlikely that any secondary electrons would be able to escape the surface due to the positive substrate bias potential.