Influence of sputtering conditions and electron energy on XPSdepth profiling of Ge in SiO2

Ge nanocluster formation in SiO2 is of growing interest for new electronic applications. Ion beam synthesis using high-energy Ge implantation connected with thermal annealing is one possible preparation method of such clusters. In addition to investigations of electrical and structural changes during the cluster formation process we also studied chemical changes in the samples using x-ray photoelectron spectroscopy (XPS). This was done with low-energy noble gas ion sputtering for depth profiling. Binding state information one can get from the XPS data by means of factor analysis (FA) in combination with other structural investigations.
However, mixed bonding states probably created by ion beam damage during sputter erosion are dominating the results. It is shown, that by changing the experimental conditions (ion beam impact depth during sputtering, electron information depth during XPS measurement) these mixed states are influenced in an appropriate manner. It is concluded that useful chemical information on the behavior of the implanted Ge can be derived despite of the ion beam damage.