Abstract
In this study, we investigated the electronic surface structure of donor-doped strontium titanate. Homoepitaxial 0.5 wt. % donor-doped SrTiO3 thin films were analyzed by in situ near ambient pressure X-ray photoelectron spectroscopy at a temperature of 770 K and oxygen pressures up to 5 mbar. Upon exposure to an oxygen atmosphere at elevated temperatures, we observed a rigid binding energy shift of up to 0.6 eV towards lower binding energies with respect to vacuum conditions for all SrTiO3 core level peaks and the valence band maximum with increasing oxygen pressure. The rigid shift is attributed to a relative shift of the Fermi energy towards the valence band concomitant with a negative charge accumulation at the surface, resulting in a compensating electron depletion layer in the near surface region. Charge trapping effects solely based on carbon contaminants are unlikely due to their irreversible desorption under the given experimental conditions. In addition, simple reoxygenation of oxygen vacancies c...
Highlights
Recent research on n-SrTiO3 indicated the existence of a surface space charge layer rendering its surface properties more complex: Ohtomo et al observed a surface electron depletion in La-doped SrTiO3 thin films at temperatures below 300 K and related it to an intrinsic surface pinning potential of about 0.7 eV.[11]
Mikheev et al attributed the magnitude of the resistive switching properties of a Pt/Nb-doped SrTiO3 (Nb):SrTiO3 junction to charges trapped in an unintentional contamination layer.[4]
Connected a surface band bending to anti-domain boundaries in different reconstructions of the SrTiO3 (110) surface after annealing treatments in different pO2.12 Marchewka et al revealed the existence of an electron depletion layer in Pt/Fe:SrTiO3/Nb:SrTiO3 structures extending into the
Summary
Oxygen partial pressure dependence of surface space charge formation in donor-doped SrTiO3
Published Version (Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have