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Visible-light-accelerated oxygen vacancy migration in strontium titanate.

Li Y, Lei Y, Shen BG, Sun JR - Sci Rep (2015)

Bottom Line: 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.This effect provides a feasible approach towards the modulation of the anionic processes.

View Article: PubMed Central - PubMed

Affiliation: Beijing National Laboratory for Condensed Matter &Institute of Physics, Chinese Academy of Sciences, Beijing 100190, Peoples' Republic of China.

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.

No MeSH data available.


Related in: MedlinePlus

Transient current through biased STO.(a) A sketch of the experimental setup for transient current measurements. (b) Transient current for VG = −80 V and P = 0, measured under different temperatures. Arrow marks the position of current peak. (c) Transient current for VG = −80 V and P = 100 W (λ = 532 nm). (d) Semi-logarithmic plot of the vacancy mobility against reciprocal temperature. Solid lines are guides for the eye. (e) Transient current measured under different light powers (VG = −400 V, λ = 532 nm). (f) Activation energies of oxygen vacancies obtained by different groups (refs 18, 19, 20). Our results are represented by two red symbols (marked by two arrows). Dashed lines are guides for the eye.
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f3: Transient current through biased STO.(a) A sketch of the experimental setup for transient current measurements. (b) Transient current for VG = −80 V and P = 0, measured under different temperatures. Arrow marks the position of current peak. (c) Transient current for VG = −80 V and P = 100 W (λ = 532 nm). (d) Semi-logarithmic plot of the vacancy mobility against reciprocal temperature. Solid lines are guides for the eye. (e) Transient current measured under different light powers (VG = −400 V, λ = 532 nm). (f) Activation energies of oxygen vacancies obtained by different groups (refs 18, 19, 20). Our results are represented by two red symbols (marked by two arrows). Dashed lines are guides for the eye.

Mentions: A further question is how photo-excitation accelerates the gating effect. As suggested by Hanzig et al.6, the structural deformed phase forms while oxygen vacancies drift along electric field. In this scenario, photo-excitation may affect the gating effect through accelerating vacancy diffusion. To reveal the effect of light illumination on oxygen vacancies, transient current, i(t), through an electrically biased STO is studied in the presence (absence) of light illumination. Figure 3a is a schematic experimental setup. Figure 3b,c display the transient current as a function of time, recorded by fixing VG to − 80 V at a temperature between 328 K and 408 K. With the increase of t, the transient current undergoes first a low to high and then a high to low transition, leaving a current peak at τp. This feature is observed in all i(t) curves acquired at different temperatures. Comparing with the data without light, we found that light illumination causes an obvious left shift of current peak. This phenomenon is particularly evident when temperature is not very high. For example, at a temperature of 328 K, τp is ~2100 s in light but ~24970 s without light, i.e., the time required to reach the current peak has been reduced by more than one order of magnitude by light illumination. This result implies an acceleration of vacancy diffusion. As well established, the transient current is carried by VOs, and the transient current gets a maximum when the oxygen vacancies underneath anode arrive at cathode628.


Visible-light-accelerated oxygen vacancy migration in strontium titanate.

Li Y, Lei Y, Shen BG, Sun JR - Sci Rep (2015)

Transient current through biased STO.(a) A sketch of the experimental setup for transient current measurements. (b) Transient current for VG = −80 V and P = 0, measured under different temperatures. Arrow marks the position of current peak. (c) Transient current for VG = −80 V and P = 100 W (λ = 532 nm). (d) Semi-logarithmic plot of the vacancy mobility against reciprocal temperature. Solid lines are guides for the eye. (e) Transient current measured under different light powers (VG = −400 V, λ = 532 nm). (f) Activation energies of oxygen vacancies obtained by different groups (refs 18, 19, 20). Our results are represented by two red symbols (marked by two arrows). Dashed lines are guides for the eye.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4588568&req=5

f3: Transient current through biased STO.(a) A sketch of the experimental setup for transient current measurements. (b) Transient current for VG = −80 V and P = 0, measured under different temperatures. Arrow marks the position of current peak. (c) Transient current for VG = −80 V and P = 100 W (λ = 532 nm). (d) Semi-logarithmic plot of the vacancy mobility against reciprocal temperature. Solid lines are guides for the eye. (e) Transient current measured under different light powers (VG = −400 V, λ = 532 nm). (f) Activation energies of oxygen vacancies obtained by different groups (refs 18, 19, 20). Our results are represented by two red symbols (marked by two arrows). Dashed lines are guides for the eye.
Mentions: A further question is how photo-excitation accelerates the gating effect. As suggested by Hanzig et al.6, the structural deformed phase forms while oxygen vacancies drift along electric field. In this scenario, photo-excitation may affect the gating effect through accelerating vacancy diffusion. To reveal the effect of light illumination on oxygen vacancies, transient current, i(t), through an electrically biased STO is studied in the presence (absence) of light illumination. Figure 3a is a schematic experimental setup. Figure 3b,c display the transient current as a function of time, recorded by fixing VG to − 80 V at a temperature between 328 K and 408 K. With the increase of t, the transient current undergoes first a low to high and then a high to low transition, leaving a current peak at τp. This feature is observed in all i(t) curves acquired at different temperatures. Comparing with the data without light, we found that light illumination causes an obvious left shift of current peak. This phenomenon is particularly evident when temperature is not very high. For example, at a temperature of 328 K, τp is ~2100 s in light but ~24970 s without light, i.e., the time required to reach the current peak has been reduced by more than one order of magnitude by light illumination. This result implies an acceleration of vacancy diffusion. As well established, the transient current is carried by VOs, and the transient current gets a maximum when the oxygen vacancies underneath anode arrive at cathode628.

Bottom Line: 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.This effect provides a feasible approach towards the modulation of the anionic processes.

View Article: PubMed Central - PubMed

Affiliation: Beijing National Laboratory for Condensed Matter &Institute of Physics, Chinese Academy of Sciences, Beijing 100190, Peoples' Republic of China.

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.

No MeSH data available.


Related in: MedlinePlus