Abstract
Strontium titanate is a model transition metal oxide that exhibits versatile properties of special interest for both fundamental and applied researches. There is evidence that most of the attractive properties of SrTiO3 are closely associated with oxygen vacancies. Tuning the kinetics of oxygen vacancies is then highly desired. Here we reported on a dramatic tuning of the electro-migration of oxygen vacancies by visible light illumination. It is found that, through depressing activation energy for vacancy diffusion, light illumination remarkably accelerates oxygen vacancies even at room temperature. This effect provides a feasible approach towards the modulation of the anionic processes. The principle proved here can be extended to other perovskite oxides, finding a wide application in oxide electronics.
Highlights
It is obvious that light illumination generates extra charge carriers by exciting the in-gap states of STO, leading to the growth of sheet conductance
Comparing with the data without light, we found that light illumination causes an obvious left shift of current peak
The above experiments suggest that light illumination accelerates field-induced lattice expansion via accelerating oxygen vacancy diffusion (Figs 1 and 3), and this acceleration process occurs accompanying the photo-excitation of in-gap states of STO (Fig. 2)
Summary
6, structural deformation occurs accompanying the electro-migration of VOs, these results suggest a mobilization of oxygen vacancies by light illuminating. It is obvious that light illumination generates extra charge carriers by exciting the in-gap states of STO (photon energy is lower than the band gap of STO), leading to the growth of sheet conductance.
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