These XPS spectra were recorded on an electrical contact prepared on a silicon wafer from titanium and silver. The sample was heat-treated causing diffusion of the components. The upper layers were oxidised and the top surface was contaminated by carbon. Ion etch series were performed by 2 keV Ar+ ions in 2 min steps.
The ion etch depth profile reflects the changes seen on the previous figure. Beside the intensity (height) changes of the lines consider alterations in FWHM as well; this explains the shallower concentration differences visible in the Ti profile. The reduction of the system can be seen from not only the chemical shift changes but the decreasing oxygen balance, as well.
I. Bertóti, A. Tóth, M. Mohai:
Szilícium napelemeken kialakított fémkontaktusok XPS vizsgálata.
(XPS Investigation of Metal Contacts Prepared on Silicon Solar Cells.)
Research report (unpublished).