From the TEM analysis it is seen that both the deposited iron and the un-coated silicon oxide substrate material has a very rough morphology with height variations of 50 nm. As we cannot deposit an oxidation-blocking cap layer after the metal deposition in our deposition system, we deposit thicker Fe films to avoid complete oxidation of the very oxyphilic Fe film. This meant that we used much longer processing times than needed for any relevant application in nanometer scaled electronic applications where typical film thicknesses of only a few tens of nm are needed. From Figure it is seen that the first approximately 100 nm close to the Ag interface is significantly denser as compared to the top surface. This region is also more than a relevant film thickness for electronics applications. The longer deposition meant that whatever mechanism causing the increased surface roughness on the SiO2 was exaggerated. Thus, deposition of thinner Fe films is expected to significantly reduce the surface roughness on the SiO2. We speculate that the roughening mechanism is somewhat similar to preferential sputtering of insulating layers in asymmetric bipolar DC-sputtering discharges, as described by Sellers. The insulating SiO2 forms a parasitic capacitor, which leads to the plasma-facing surface of the insulator to be charged toward -40 V when applying +40 V to the sample holder. This opens for positive ion acceleration towards the SiO2 surface and thereby etching of the top surface. There is also the possibility that we build up voltage on the compound which could cause a breakdown of these parasitic capacitors, also resulting in increased surface roughness. High resolution XPS of the Fe spectral region recorded from the Si/SiO2 substrate areas with and without Ag coating (Figure ) show that the films deposited on the Ag coated areas consist of iron, confirming the EDS analysis (Figures and). The XPS analysis show that the films deposited on the Ag coated areas are mixed iron oxides in the as-deposited, untreated, samples. The Fe 2p region (Figure ) shows peaks at 709.5-711.5 eV, corresponding to Fe-O. It should be noted that these samples were subjected to air prior to being loaded into the XPS chamber and given the oxyphilic nature of iron, surface oxidation is expected. Film deposition was also done in medium vacuum meaning that low levels of oxygen exposure is to be expected during the deposition. The films where therefore sputter cleaned in the XPS chamber. After 1800 s sputtering, shoulder peaks at 706.9 and 720.1 eV (Δ13.2 eV) corresponding to zero valent Fe 2p3/2 and Fe 2p1/2, respectively can be seen (Figure ).