Sputter-induced reduction

Sputter-induced Roughness. Sputtering single crystal semiconductors, in particular II-VI semiconductors, with Cs" ions results in surface roughening. There is currently no satisfactory explanation of this effect. This effect, and the corresponding reduction of the depth resolution, can be avoided by rotating the sample during the measurement. 

Figure 9.15. Influence of sample cleaning on XPS scans taken on a thin-film superconductor, (a) Survey scan from an as-received surface, (b) Survey scan from surface after ion-beam (sputter) cleaning. Note the reduction in the Cls peak after cleaning, (c) Comparative Ba3d scans from both cases. Note the change in shape and size as the surface contaminant layers (probably containing carbonates and hydroxides of Ba in addition to other components) are removed. The peak shapes and intensities of other cations change, too. Initial data represent the composition and chemistry of the contaminant layer, whereas that from sputtered sample represents those of the pure underlying superconductor (possibly with sputter-induced changes that need to be accounted for).

Although the ability of sulfur dioxide to create sulfides on metal smfaces has been asserted previously [54, 58] and in metals like copper the sulfides are common constituents in the atmospheric corrosion products [59], in the case of zinc these compoimds are rare [5]. More likely is that the sputtering induces the reduction of sulfite, which does not allow obtaining reliable in-depth measurements of the layer of corrosion products of zinc exposed in sulfur environments. 

Fig. 10.23 displays the results for the thickness calibration of sputtered TaN, TaON, Ag, and co-sputtered TaON—Ag layers on the polyester. The fastest bacterial inactivation kinetics was observed for co-sputtered TaON-Ag layers for 2 min and attained coatings about 130 nm thick. This is equivalent to 650 layers. Assuming each layer is 10 atoms/cm, a deposition rate of about 5.4 x 10 atoms/cm s can be estimated." Work in our laboratory showed faster bacterial inactivation of E. coli on Ag films sputtered by DCP compared with DC-sputtered Ag films. The results obtained for bacterial reduction show that thin Ag-TaON thicknesses below 50 nm were not to be effective in inducing fast bacterial inactivation kinetics. 

An example of the reduction in the work-function imparted by the presence of Cesium on and within a Silicon surface (that induced by the fraction implanted in Silicon on sputtering with a Cs primary ion beam) is shown in Figure 3.21. The inset of Figure 3.21 shows the resulting variations in the Si and Si secondary ion intensities from the aforementioned Silicon substrate as a function of concentration of Cesium implanted into the Silicon substrate. As can be seen, the positive secondary ions are quenched in an exponential-like manner with increasing Cesium content, whereas the positive secondary ions are enhanced, also in an exponential-like manner. These trends can be described by the relations ... 

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