Oxygen incorporation into strontium titanate single crystals from CO2 dissociation

Abstract

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.