Study of surface states of SrTiO3 (001) under elevated oxygen pressure condition using AP-XPS

Abstract

Using ambient pressure X-ray photoelectron spectroscopy (AP-XPS), surface states of SrTiO3 (001) single crystal was monitored. Under O2 0.1 mbar condition, SrO1+x surface oxide was observed at all measurement temperatures while SrO1+x oxide started to appear when substrate temperature reached to 600℃ in UHV condition. Interestingly, the binding energy offset appears in SrO1+x spectra between O2 gaseous and UHV condition, indicating the presence of band bending in O2 annealing process due to the Sr vacancy formation. The analysis of AP-XPS results shows the onset of modified surface electronic structure of SrTiO3 during oxygen annealing condition.