| 1. |
- Cacucci, Arnaud, et al.
(författare)
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Flash annealing influence on structural and electrical properties of TiO2/TiO/Ti periodic multilayers
- 2014
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 553, s. 47-51
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Tidskriftsartikel (refereegranskat)abstract
- Multilayered structures with a 40 nm period composed of titanium and two different titanium oxides, TiO and TiO2, were accurately produced by DC magnetron sputtering using the reactive gas pulsing process. These multilayers were sputtered onto Al2O3 sapphire to avoid substrate compound diffusion during flash annealing ( ranging from 350 degrees C to 550 degrees C). Structure and composition of these periodic TiO2/TiO/Ti stacks were investigated by X-ray diffraction, X-ray photoemission spectroscopy and transmission electronic microscopy techniques. Two crystalline phases alpha-Ti and fcc-TiO were identified in the metallic-rich sub-layers whereas the oxygen-rich ones were composed of a mixture of amorphous and rutile TiO2 phase. DC electrical resistivity. measured for temperatures ranging from 25 to 200 degrees C was influenced by the thermal treatments. The temperature coefficients of resistance of these periodic TiO2/TiO/Ti multilayers were modified from 11.7 x 10(-04) to -8.81 x 10(-04) K-1. Local changes of crystallinity were reported and the resistivity responses of these annealed films could be linked to the typical electrical behavior of a metal-oxide mixture.
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| 2. |
- Cacucci, Arnaud, et al.
(författare)
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The interdependence of structural and electrical properties in TiO2/TiO/Ti periodic multilayers
- 2013
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Ingår i: Acta Materialia. - : Elsevier BV. - 1359-6454 .- 1873-2453. ; 61:11, s. 4215-4225
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Tidskriftsartikel (refereegranskat)abstract
- Multilayered structures with 14-50 nm periods composed of titanium and two different titanium oxides, TiO and TiO2, were accurately produced by DC magnetron sputtering using the reactive gas pulsing process. The structure and composition of these periodic TiO2/TiO/Ti stacks were investigated by X-ray diffraction and transmission electronic microscopy techniques. Two crystalline phases, hexagonal close packed Ti and face centred cubic TiO, were identified in the metallic-rich sub-layers, whereas the oxygen-rich ones comprised a mixture of amorphous TiO2 and rutile phase. DC electrical resistivity rho measured for temperatures ranging from 300 to 500 K exhibited a metallic-like behaviour (rho(473K) = 1.05 x 10(-5) to 1.45 x 10(-6) Omega m) with a temperature coefficient of resistance ranging from 1.20 x 10(-3) K-1 for the highest period (Lambda = 50.0 nm) down to negative values close to -4.97 x 10(-4) K-1 for the smallest one (Lambda = 14.0 nm). A relationship between the dimensions of periodic layers and their collective electrical resistivity is proposed where the resistivity does not solely depend on the total thickness of the film, but also depends on the chemical composition and thickness of each sub-layer. Charge carrier mobility and concentration measured by the Hall effect were both influenced by the dimension of TiO2/TiO/Ti periods and the density of ionized scattering centres connected to the titanium concentration in the metallic sub-layers.
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| 3. |
- Martin, Nicolas, et al.
(författare)
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Architectured columns with a metal-dielectric periodic nanostructure
- 2016
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Ingår i: Materials letters (General ed.). - : Elsevier BV. - 0167-577X .- 1873-4979. ; 172, s. 128-131
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Tidskriftsartikel (refereegranskat)abstract
- We engineer a sputter deposited metal/oxide periodic structure based on W and Ta, and corresponding oxides with tuneable alternations from a few nanometers to a few tens nanometers, combined with the preparation of inclined, zigzag and spiral columns. This work shows how bi-component periodic multilayers can be produced within some inclined nano-columns exhibiting oriented, zigzag and helix structures. This unique combination of controlled columnar structure and periodic multilayers enables new opportunities to create some unusual structural designs for functional materials.
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