13:30-15:00
Automated XPS analysis and XPS-Imaging of nano-structures
Prof. Sven Tougaard(Department of Physics and Chemistry, University of Southern Denmark)
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The technological importance of nano-structures is continuously increasing. XPS is one of the most effective methods to characterize nano-structures. This has led to a strong increase in the use of XPS and a demand for accurate and automated XPS analysis. At the same time, non-destructive three dimensional imaging of surface nano-structures has also become of increasing importance for industry.
To meet this demand, an algorithm for non-destructive XPS analysis which is suitable for automation was developed[1]. For each XPS spectrum, this algorithm determines two numbers: the total amount of atoms within the outermost ~ 10 nm and their approximate depth. In the talk we will summarize the technique and through practical examples demonstrate its potentials for both automation of conventional XPS data analysis and for 3D XPS imaging.
[1]S. Tougaard, J. Vac. Sci. Technol., A21 (2003) 1081; A23(2005) 741
Extrinsic and intrinsic effects in XPS: Validity of the two-step model and corrections for surface and core-hole effects
- We summarize some of the models applied for interpretation of photoelectron emission spectra. The models are compared and their validity is discussed by comparison to various sets of experiments.
It is found that the two step model gives a reasonable description of the rough processes. However, in particular at lower energies, the more detailed effects are only well described by a one-step model which includes effects of the core hole and of the surface. It is found that the semi-classical dielectric response model[1] gives a fairly good quantitaive description.
Finally a new correction parameter CPXPS is introduced[2]. This takes into account the effects of the core hole and the surface excitations. This is similar to the surface excitation parameter (SEP) used in REELS but its dependence on geometry is different and its magnitude is in general much larger due to the presence of the core hole.
[1]Simonsen, Yubero, Tougaard, Phys Rev B56, 1612 (1997)
[2]Pauly, Tougaard; Surf. Sci. 604, 1193 (2010)S. Tougaard, J. Vac. Sci. Technol., A21 (2003) 1081; A23(2005) 741