Oxygen incorporation into strontium titanate single crystals from CO2 dissociation

Oxygen incorporation from CO2 into Fe-doped SrTiO3(100) single crystals (0.013 at% Fe, 0.039 at% Fe and 0.13 at% Fe) was investigated. Oxygen incorporation processes using 13C18O2 as the gas source were studied by isotope exchange depth profiling (IEDP) and subsequent secondary-ion mass spectroscopy (SIMS). The interaction of CO2 with SrTiO3 (100) surfaces was further studied with different surface analytical techniques like metastable induced electron spectroscopy (MIES), ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS). Results indicate that CO2 interaction with SrTiO3 (100) surfaces does not change the surface at all. It seems that CO2 provides a very low sticking probability on the surface as it is not traced by valence band spectroscopy even at room temperature. Nonetheless, 13C18O2 acts as an incorporation source of 18O into the Fe-doped SrTiO3 single crystals. The diffusion coefficient exhibits a peculiar behaviour when Fe concentration increases. No carbon incorporation is observed at all.