摘要
The oxygen vacancies in the SrTiO 3 (STO) single crystal with two different cap layers, CoFe 2 O 4 (CFO) and BiFeO 3 (BFO), are investigated with the technique of electron paramagnetic resonance (EPR). EPR spectra show the resonance lines of the residual oxygen vacancy in air annealed STO, STO/CFO, and STO/BFO, showing the high sensitivity of EPR to the low concentration defects. The experimental results indicate that the oxide cap layers enhance the oxygen deficiency in bulk STO and the amount of oxygen vacancy is dependent on the electronegativity of metal ion in the cap layer. Accordingly, STO/BFO has a larger amount of oxygen vacancy than that of STO/CFO. © 2012 American Institute of Physics.