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Electronic Conduction in Ti/Poly-TiO2/Ti Structures.

Hossein-Babaei F, Alaei-Sheini N - Sci Rep (2016)

Bottom Line: Containing no interface energy barrier, Ti/poly-TiO2/Ti devices demonstrate high resistance ohmic conduction at biasing fields below 5 × 10(6) V.m(-1); higher fields drive the samples to a distinctly nonlinear and hysteretic low resistance status.The observed threshold is two orders of magnitude smaller than the typical resistance switching fields reported for the nanosized single grain memristors.This is consistent with the smaller activation energies reported for the IOV motion on the rutile facets than its interior.

View Article: PubMed Central - PubMed

Affiliation: Electronic Materials Laboratory, Electrical Engineering Department, K. N. Toosi University of Technology, Tehran 16317-14191, Iran.

ABSTRACT
Recent intensive investigations on metal/metal oxide/metal structures have targeted nanometric single grain oxides at high electric fields. Similar research on thicker polycrystalline oxide layers can bridge the results to the prior literature on varistors and may uncover novel ionic/electronic features originating from the conduction mechanisms involving grain boundaries. Here, we investigate electronic conduction in Ti/poly-TiO2-x/Ti structures with different oxygen vacancy distributions and describe the observed features based on the motion and rearrangement of the ionized oxygen vacancies (IOVs) on the grain facets rather than the grain interiors. Containing no interface energy barrier, Ti/poly-TiO2/Ti devices demonstrate high resistance ohmic conduction at biasing fields below 5 × 10(6) V.m(-1); higher fields drive the samples to a distinctly nonlinear and hysteretic low resistance status. The observed threshold is two orders of magnitude smaller than the typical resistance switching fields reported for the nanosized single grain memristors. This is consistent with the smaller activation energies reported for the IOV motion on the rutile facets than its interior. The presented model describes the observed dependence of the threshold field on the relative humidity of the surrounding air based on the lower activation energies reported for the hydroxyl-assisted IOV motion on the rutile facets.

No MeSH data available.


Related in: MedlinePlus

The Arrhenius diagrams of the electric conduction.(a) In an A-sample and (b) in a B-sample; measurements are carried out at the stated applied fields in clean air with 23% relative humidity. The inset gives the variations of the obtained activation energies with respect to the biasing field.
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f3: The Arrhenius diagrams of the electric conduction.(a) In an A-sample and (b) in a B-sample; measurements are carried out at the stated applied fields in clean air with 23% relative humidity. The inset gives the variations of the obtained activation energies with respect to the biasing field.

Mentions: The activation energy of the electronic conduction (ΔEa) (should not be mistaken with the activation energy of IOV motion (∆Ua)) in both sample categories is investigated by plotting the Arrhenius diagrams of conduction at different biasing fields. The diagrams obtained for A- and B-samples are given in Fig. 3a,b, respectively. As demonstrated in these figures, the estimated ΔEa values in both sample types vary with the applied electric field. The resulted ΔEa vs. applied field plots are given as insets in Fig. 3a,b. The current levels recorded for A-samples (Fig. 3a) are 103 times smaller than those in B-samples (Fig. 3b), allowing electrons to select the easiest path available. There is no significant IOV migration in A-samples, and higher applied fields force the electrons to the non-optimum paths with higher activation energies causing the increase in the overall activation energy deduced from the Arrhenius diagrams (see the inset in Fig. 3a). In B-samples, on the other hand, according to the inset in Fig. 3b, ΔEa of conduction drops from 0.5 eV to 0.3 eV when the electric field is increased from 0.5 MV/m to 10 MV/m. This is attributed to the rearrangement of the IOVs at biasing fields above 5 MV/m, which create easier conduction routes for electrons. Biasing fields insufficient to cause IOV motion hardly affect ΔEa which remains independent from the external field at 0.5 eV. Assuming electron hopping between IOVs to be the foremost conduction mechanism54, the observed reduction in ΔEa is consistent with the IOV motion for filament formation. This conduction mechanism is complex, involving electron hopping between traps whose average distance varies with the progress of the filament formation process. A quantitative description of the forward segment in the I–V diagram of a B-sample, hence, requires development of a novel model.


Electronic Conduction in Ti/Poly-TiO2/Ti Structures.

Hossein-Babaei F, Alaei-Sheini N - Sci Rep (2016)

The Arrhenius diagrams of the electric conduction.(a) In an A-sample and (b) in a B-sample; measurements are carried out at the stated applied fields in clean air with 23% relative humidity. The inset gives the variations of the obtained activation energies with respect to the biasing field.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4940738&req=5

f3: The Arrhenius diagrams of the electric conduction.(a) In an A-sample and (b) in a B-sample; measurements are carried out at the stated applied fields in clean air with 23% relative humidity. The inset gives the variations of the obtained activation energies with respect to the biasing field.
Mentions: The activation energy of the electronic conduction (ΔEa) (should not be mistaken with the activation energy of IOV motion (∆Ua)) in both sample categories is investigated by plotting the Arrhenius diagrams of conduction at different biasing fields. The diagrams obtained for A- and B-samples are given in Fig. 3a,b, respectively. As demonstrated in these figures, the estimated ΔEa values in both sample types vary with the applied electric field. The resulted ΔEa vs. applied field plots are given as insets in Fig. 3a,b. The current levels recorded for A-samples (Fig. 3a) are 103 times smaller than those in B-samples (Fig. 3b), allowing electrons to select the easiest path available. There is no significant IOV migration in A-samples, and higher applied fields force the electrons to the non-optimum paths with higher activation energies causing the increase in the overall activation energy deduced from the Arrhenius diagrams (see the inset in Fig. 3a). In B-samples, on the other hand, according to the inset in Fig. 3b, ΔEa of conduction drops from 0.5 eV to 0.3 eV when the electric field is increased from 0.5 MV/m to 10 MV/m. This is attributed to the rearrangement of the IOVs at biasing fields above 5 MV/m, which create easier conduction routes for electrons. Biasing fields insufficient to cause IOV motion hardly affect ΔEa which remains independent from the external field at 0.5 eV. Assuming electron hopping between IOVs to be the foremost conduction mechanism54, the observed reduction in ΔEa is consistent with the IOV motion for filament formation. This conduction mechanism is complex, involving electron hopping between traps whose average distance varies with the progress of the filament formation process. A quantitative description of the forward segment in the I–V diagram of a B-sample, hence, requires development of a novel model.

Bottom Line: Containing no interface energy barrier, Ti/poly-TiO2/Ti devices demonstrate high resistance ohmic conduction at biasing fields below 5 × 10(6) V.m(-1); higher fields drive the samples to a distinctly nonlinear and hysteretic low resistance status.The observed threshold is two orders of magnitude smaller than the typical resistance switching fields reported for the nanosized single grain memristors.This is consistent with the smaller activation energies reported for the IOV motion on the rutile facets than its interior.

View Article: PubMed Central - PubMed

Affiliation: Electronic Materials Laboratory, Electrical Engineering Department, K. N. Toosi University of Technology, Tehran 16317-14191, Iran.

ABSTRACT
Recent intensive investigations on metal/metal oxide/metal structures have targeted nanometric single grain oxides at high electric fields. Similar research on thicker polycrystalline oxide layers can bridge the results to the prior literature on varistors and may uncover novel ionic/electronic features originating from the conduction mechanisms involving grain boundaries. Here, we investigate electronic conduction in Ti/poly-TiO2-x/Ti structures with different oxygen vacancy distributions and describe the observed features based on the motion and rearrangement of the ionized oxygen vacancies (IOVs) on the grain facets rather than the grain interiors. Containing no interface energy barrier, Ti/poly-TiO2/Ti devices demonstrate high resistance ohmic conduction at biasing fields below 5 × 10(6) V.m(-1); higher fields drive the samples to a distinctly nonlinear and hysteretic low resistance status. The observed threshold is two orders of magnitude smaller than the typical resistance switching fields reported for the nanosized single grain memristors. This is consistent with the smaller activation energies reported for the IOV motion on the rutile facets than its interior. The presented model describes the observed dependence of the threshold field on the relative humidity of the surrounding air based on the lower activation energies reported for the hydroxyl-assisted IOV motion on the rutile facets.

No MeSH data available.


Related in: MedlinePlus