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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 drift velocities of the doubly ionized oxygen vacancy in/on a rutile grain.Calculations are carried out for the IOV motion in the [110] direction inside (blue) and on a (110) surface (red) of a single crystalline grain, the results are plotted vs. the applied field. The curves intersect the 2 × 10−7 m/s tie line (green) at field intensities almost 3 orders of magnitude apart. These comparative calculations are based on the theoretical relationship presented in ref. 29.
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f4: The drift velocities of the doubly ionized oxygen vacancy in/on a rutile grain.Calculations are carried out for the IOV motion in the [110] direction inside (blue) and on a (110) surface (red) of a single crystalline grain, the results are plotted vs. the applied field. The curves intersect the 2 × 10−7 m/s tie line (green) at field intensities almost 3 orders of magnitude apart. These comparative calculations are based on the theoretical relationship presented in ref. 29.

Mentions: The results given in Fig. 4 indicate that the external field intensity required to reach the same speed (see the tie line in Fig. 4) differs by about 3 orders of magnitude among ionic species with respective motion activation energies of 0.5 and 1.1 eV. These comparative calculations explain the observed difference in the onset fields of the single-grain and poly-crystalline Ti/rutile/Ti devices. Figure 4 also shows that the curves obtained for two different activation energies have very different slopes at their points of IOV motion initiation. This translates into a controllable change of resistance with field intensity in the polycrystalline samples compared to the sudden and hardly containable change of status in a single grain device. This is verified by observing the controllability of the operating point all over the I–V diagrams of our samples.


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

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

The drift velocities of the doubly ionized oxygen vacancy in/on a rutile grain.Calculations are carried out for the IOV motion in the [110] direction inside (blue) and on a (110) surface (red) of a single crystalline grain, the results are plotted vs. the applied field. The curves intersect the 2 × 10−7 m/s tie line (green) at field intensities almost 3 orders of magnitude apart. These comparative calculations are based on the theoretical relationship presented in ref. 29.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f4: The drift velocities of the doubly ionized oxygen vacancy in/on a rutile grain.Calculations are carried out for the IOV motion in the [110] direction inside (blue) and on a (110) surface (red) of a single crystalline grain, the results are plotted vs. the applied field. The curves intersect the 2 × 10−7 m/s tie line (green) at field intensities almost 3 orders of magnitude apart. These comparative calculations are based on the theoretical relationship presented in ref. 29.
Mentions: The results given in Fig. 4 indicate that the external field intensity required to reach the same speed (see the tie line in Fig. 4) differs by about 3 orders of magnitude among ionic species with respective motion activation energies of 0.5 and 1.1 eV. These comparative calculations explain the observed difference in the onset fields of the single-grain and poly-crystalline Ti/rutile/Ti devices. Figure 4 also shows that the curves obtained for two different activation energies have very different slopes at their points of IOV motion initiation. This translates into a controllable change of resistance with field intensity in the polycrystalline samples compared to the sudden and hardly containable change of status in a single grain device. This is verified by observing the controllability of the operating point all over the I–V diagrams of our samples.

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