AC electrical properties of TiO2 and Magnéli phases, TinO2n−1

Regonini, D.; Adamaki, Vana; Bowen, Chris R.; Pennock, S.R.; Taylor, J.; Dent, Andrew C E

doi:10.1016/j.ssi.2012.10.003

Cited by 47 publications

(35 citation statements)

References 41 publications

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“…Interestingly, even in dark conditions the material is significantly conductive. At 10V, for example, it has a conductivity of ~ 6·10 -4 S·m -1 , which is comparable to that of monolithic TiO2 with grain size in the range of tens of microns, 20 but orders of magnitude superior to that of sintered mesoporous TiO2 materials, ordered mesoporous TiO2 from block-copolymer directed growth, as well as other morphologies used in photodetectors, all in the 10 -8 S/m range. 9,10,21,22 This is due to the network of nanocrystals discussed above, which minimises the activation energy for charge transfer between adjacent crystalline domains, with the added benefit of oxygen vacancies acting as donors.…”

Section: Resultsmentioning

confidence: 94%

Highly responsive UV-photodetectors based on single electrospun TiO₂ nanofibres

et al. 2016

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In this work we study the optoelectronic properties of individual TiO2 fibres produced through coupled sol-gel and electrospinning, by depositing them onto pre-patterned Ti/Au electrodes on SiO2/Si substrates. Transport measurements in the dark give a conductivity above 2·10 -5 S, which increases up to 8·10 -5 S in vacuum. Photocurrent measurements under UV-irradiation show high sensitivity (responsivity of 90 A·W -1 for 375 nm wavelength) and a response time to illumination of ~ 5 s, which is superior to state-of-the-art TiO2-based UV photodetectors. Both responsivity and response speed are higher in air than in vacuum, due to oxygen adsorbed on the TiO2 surface which traps photoexcited free electrons in the conduction band, thus reducing the recombination processes. The photodetectors are sensitive to light polarization, with an anisotropy ratio of 12%. These results highlight the interesting combination of large surface area and low 1D transport resistance in electrospun TiO2 fibres. The simplicity of the sol-gel/electrospinning synthesis method, combined with a fast response and high responsivity makes them attractive candidates for UV-photodetection in ambient conditions. We anticipate their high (photo) conductance is also relevant for photocatalysis and dye-sensitized solar cells.

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Section: Resultsmentioning

confidence: 94%

Highly responsive UV-photodetectors based on single electrospun TiO₂ nanofibres

et al. 2016

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“…In a 4F 2 dense crossbar array configuration, these various device structures would yield a line resistance of R l = 2ρ Pt / h (where ρ Pt is the resistivity of Pt), which can vary in between 21.2 and 2.12 . Concurrently, the range of parasitic capacitance C p of these structures (calculated as: C p = ε 0 ε TiO 2 F 2 /d, where ε 0 is the permittivity of free space and ε TiO 2 = 100 is the room temperature dc relative permittivity of TiO 2 [22]) is shown in Fig. 8(e) and can be contained in the range of 1 aF-10 pF.…”

Section: Discussionmentioning

confidence: 99%

A <inline-formula> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>-Controller-Based System for Interfacing Selectorless RRAM Crossbar Arrays

Berdan

Serb

Khiat

et al. 2015

IEEE Trans. Electron Devices

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Abstract-Selectorless crossbar arrays of resistive randomaccess memory (RRAM), also known as memristors, conduct large sneak currents during operation, which can significantly corrupt the accuracy of cross-point analog resistance (M t ) measurements. In order to mitigate this issue, we have designed, built, and tested a memristor characterization and testing (mCAT) instrument that forces redistribution of sneak currents within the crossbar array, dramatically increasing M t measurement accuracy. We calibrated the mCAT using a custom-made 32 × 32 discrete resistive crossbar array, and subsequently demonstrated its functionality on solid-state TiO 2−x RRAM arrays, on wafer and packaged, of the same size. Our platform can measure standalone M t in the range of 1 k to 1 M with <1% error. For our custom resistive crossbar, 90% of devices of the same resistance range were measured with <10% error. The platform's limitations have been quantified using large-scale nonideal crossbar simulations.

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“…26 This value is believed to be contributing to the DC conductivity, and this DC contribution becomes so dominant at T ‡ 1000 K that r ac (f, T) = r T (0) over 0.1 Hz ‡ f £ 10 6 Hz. 27 The second regime is related to an increase in r ac (f, T) from r T (0) at a cross-over frequency of f % 10 kHz. Thirdly, r ac (f, T) is found to be increasingly independent of temperature for the high-frequency range f ‡ 100 kHz.…”

Section: Dependence Of Conductivity On Frequency and Temperaturementioning

confidence: 99%

Dielectric Measurements on Sol–Gel Derived Titania Films

Çapan

Ray

2017

Journal of Elec Materi

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Alternating current (AC) impedance measurements were performed on 37 nm thick nanostructured sol-gel derived anatase titania films on ultrasonically cleaned (100) p-silicon substrates at temperatures T ranging from 100 K to 300 K over a frequency range between 20 Hz and 1 MHz. The frequency-dependent behavior of the AC conductivity r ac (f, T) obeys the universal power law, and the values of the effective hopping barrier and hopping distance were found to be 0.79 eV and 6.7 9 10 À11 m from an analysis due to the correlated barrier-hopping model. The dielectric relaxation was identified as a thermally activated non-Debye process involving an activation energy of 41.5 meV.

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AC electrical properties of TiO2 and Magnéli phases, TinO2n−1

Cited by 47 publications

References 41 publications

Highly responsive UV-photodetectors based on single electrospun TiO₂ nanofibres

Highly responsive UV-photodetectors based on single electrospun TiO₂ nanofibres

A <inline-formula> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>-Controller-Based System for Interfacing Selectorless RRAM Crossbar Arrays

Dielectric Measurements on Sol–Gel Derived Titania Films

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AC electrical properties of TiO2 and Magnéli phases, TinO2n−1

Cited by 47 publications

References 41 publications

Highly responsive UV-photodetectors based on single electrospun TiO2 nanofibres

Highly responsive UV-photodetectors based on single electrospun TiO2 nanofibres

A <inline-formula> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>-Controller-Based System for Interfacing Selectorless RRAM Crossbar Arrays

Dielectric Measurements on Sol–Gel Derived Titania Films

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Highly responsive UV-photodetectors based on single electrospun TiO₂ nanofibres

Highly responsive UV-photodetectors based on single electrospun TiO₂ nanofibres