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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 fabrication and electric characterization methods.(a) The temperature vs. time profiles used for the oxidation and quenching of the A-samples (blue) and B-samples (red); the insets schematically demonstrate the cross-sectional oxygen vacancy distribution in the grown oxide layers. (b) The photograph of the titanium chip accommodating 16 Ti/TiO2/Ti samples positioned on the workbench with the block diagram of the experimental setup used for the I–V recordings.
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f8: The fabrication and electric characterization methods.(a) The temperature vs. time profiles used for the oxidation and quenching of the A-samples (blue) and B-samples (red); the insets schematically demonstrate the cross-sectional oxygen vacancy distribution in the grown oxide layers. (b) The photograph of the titanium chip accommodating 16 Ti/TiO2/Ti samples positioned on the workbench with the block diagram of the experimental setup used for the I–V recordings.

Mentions: Titanium oxide layers are grown on 10 mm × 10 mm × 1 mm Ti chips by thermal oxidation at 650 °C for 60 minutes in air. The samples are either cooled over night in the closed chamber of a switched-off furnace (A-samples) or air quenched from the soaking temperature on a corrugated silica-based refractory (B-samples). The temperature vs. time profiles used for the oxidation and quenching of both sample types are given in Fig. 8a. Due to the heat capacity of the Ti substrate and the refractory underneath, the cooling process for the B-samples is profoundly asymmetric and the oxide layer cools faster at the top than the bottom. The thickness of the grown oxide layers is in the 350 nm to 550 nm range. According to the obtained XRD patterns (see Supplementary, Section 1), the grown oxide layers are of rutile phase dominantly consisting of {110}-faceted grains; those grown at 500 °C are mixtures of rutile and anatase26. The micrographs given in Fig. 1 reveal a polycrystalline structure with average grain size of 50 nm for the grown oxide layer.


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

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

The fabrication and electric characterization methods.(a) The temperature vs. time profiles used for the oxidation and quenching of the A-samples (blue) and B-samples (red); the insets schematically demonstrate the cross-sectional oxygen vacancy distribution in the grown oxide layers. (b) The photograph of the titanium chip accommodating 16 Ti/TiO2/Ti samples positioned on the workbench with the block diagram of the experimental setup used for the I–V recordings.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f8: The fabrication and electric characterization methods.(a) The temperature vs. time profiles used for the oxidation and quenching of the A-samples (blue) and B-samples (red); the insets schematically demonstrate the cross-sectional oxygen vacancy distribution in the grown oxide layers. (b) The photograph of the titanium chip accommodating 16 Ti/TiO2/Ti samples positioned on the workbench with the block diagram of the experimental setup used for the I–V recordings.
Mentions: Titanium oxide layers are grown on 10 mm × 10 mm × 1 mm Ti chips by thermal oxidation at 650 °C for 60 minutes in air. The samples are either cooled over night in the closed chamber of a switched-off furnace (A-samples) or air quenched from the soaking temperature on a corrugated silica-based refractory (B-samples). The temperature vs. time profiles used for the oxidation and quenching of both sample types are given in Fig. 8a. Due to the heat capacity of the Ti substrate and the refractory underneath, the cooling process for the B-samples is profoundly asymmetric and the oxide layer cools faster at the top than the bottom. The thickness of the grown oxide layers is in the 350 nm to 550 nm range. According to the obtained XRD patterns (see Supplementary, Section 1), the grown oxide layers are of rutile phase dominantly consisting of {110}-faceted grains; those grown at 500 °C are mixtures of rutile and anatase26. The micrographs given in Fig. 1 reveal a polycrystalline structure with average grain size of 50 nm for the grown oxide layer.

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