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Author |
Clima, S.; Garbin, D.; Opsomer, K.; Avasarala, N.S.; Devulder, W.; Shlyakhov, I.; Keukelier, J.; Donadio, G.L.; Witters, T.; Kundu, S.; Govoreanu, B.; Goux, L.; Detavernier, C.; Afanas'ev, V.; Kar, G.S.; Pourtois, G. |
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Title |
Ovonic threshold-switching GexSey chalcogenide materials : stoichiometry, trap nature, and material relaxation from first principles |
Type |
A1 Journal article |
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Year |
2020 |
Publication  |
Physica Status Solidi-Rapid Research Letters |
Abbreviated Journal |
Phys Status Solidi-R |
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Volume |
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Issue |
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Pages |
1900672 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
Density functional theory simulations are used to identify the structural factors that define the material properties of ovonic threshold switches (OTS). They show that the nature of mobility-gap trap states in amorphous Ge-rich Ge50Se50 is related to Ge-Ge bonds, whereas in Se-rich Ge30Se70 the Ge valence-alternating-pairs and Se lone-pairs dominate. To obtain a faithful description of the electronic structure and delocalization of states, it is required to combine hybrid exchange-correlation functionals with large unit-cell models. The extent of localization of electronic states depends on the applied external electric field. Hence, OTS materials undergo structural changes during electrical cycling of the device, with a decrease in the population of less exothermic Ge-Ge bonds in favor of more exothermic Ge-Se. This reduces the amount of charge traps, which translates into coordination changes, an increase in mobility-gap, and subsequently changes in the selector-device electrical parameters. The threshold voltage drift process can be explained by natural evolution of the nonpreferred Ge-Ge bonds (or “chains”/clusters thereof) in Ge-rich GexSe1-x. The effect of extrinsic doping is shown for Si and N, which introduce strong covalent bonds into the system, increase both mobility-gap and crystallization temperature, and decrease the leakage current. |
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Wos |
000512431100001 |
Publication Date |
2020-01-28 |
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ISSN |
1862-6254 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.8 |
Times cited |
3 |
Open Access |
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Notes |
; This work was carried out in the framework of the imec Core CMOS-Emerging Memory Program. Financial support from EU H2020-NMBPTO-IND-2018 project “INTERSECT” (Grant No. 814487) is acknowledged. ; |
Approved |
Most recent IF: 2.8; 2020 IF: 3.032 |
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Call Number |
UA @ admin @ c:irua:166492 |
Serial |
6575 |
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Author |
Deng, S.; Verbruggen, S.W.; He, Z.; Cott, D.J.; Vereecken, P.M.; Martens, J.A.; Bals, S.; Lenaerts, S.; Detavernier, C. |
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Title |
Atomic layer deposition-based synthesis of photoactive TiO2 nanoparticle chains by using carbon nanotubes as sacrificial templates |
Type |
A1 Journal article |
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Year |
2014 |
Publication |
RSC advances |
Abbreviated Journal |
Rsc Adv |
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Volume |
4 |
Issue |
23 |
Pages |
11648-11653 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); Sustainable Energy, Air and Water Technology (DuEL) |
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Abstract |
Highly ordered and self supported anatase TiO2 nanoparticle chains were fabricated by calcining conformally TiO2 coated multi-walled carbon nanotubes (MWCNTs). During annealing, the thin tubular TiO2 coating that was deposited onto the MWCNTs by atomic layer deposition (ALD) was transformed into chains of TiO2 nanoparticles ([similar]12 nm diameter) with an ultrahigh surface area (137 cm2 per cm2 of substrate), while at the same time the carbon from the MWCNTs was removed. Photocatalytic tests on the degradation of acetaldehyde proved that these forests of TiO2 nanoparticle chains are highly photoactive under UV light because of their well crystallized anatase phase. |
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Wos |
000332470000017 |
Publication Date |
2014-02-14 |
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ISSN |
2046-2069; |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.108 |
Times cited |
45 |
Open Access |
Not_Open_Access |
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Notes |
; The authors wish to thank the Research Foundation – Flanders (FWO) and UGENT-GOA-01G01513 for financial support. The authors acknowledge the European Research Council for funding under the European Union's Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement no. 239865-COCOON and no. 246791-COUNTATOMS. JAM acknowledges the Flemish government for long-term structural funding (Methusalem). ; |
Approved |
Most recent IF: 3.108; 2014 IF: 3.840 |
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Call Number |
UA @ lucian @ c:irua:117298 |
Serial |
168 |
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Author |
Cremers, V.; Rampelberg, G.; Barhoum, A.; Walters, P.; Claes, N.; Oliveira, T.M. de; Assche, G.V.; Bals, S.; Dendooven, J.; Detavernier, C. |
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Title |
Oxidation barrier of Cu and Fe powder by Atomic Layer Deposition |
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A1 Journal article |
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Year |
2018 |
Publication |
Surface and coatings technology |
Abbreviated Journal |
Surf Coat Tech |
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Volume |
349 |
Issue |
349 |
Pages |
1032-1041 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
Atomic layer deposition (ALD) is a vapor based technique which allows to deposit uniform, conformal films with a thickness control at the atomic scale. In this research, Al 2 O 3 coatings were deposited on micrometer-sized Fe and Cu powder (particles) using the thermal trimethylaluminum (TMA)/ water (H 2 O) process in a rotary pump-type ALD reactor. Rotation of the powder during deposition was required to obtain a pinhole-free ALD coating. The protective nature of the coating was evaluated by quantifying its effectiveness in protecting the metal particles during oxidative annealing treatments. The Al 2 O 3 coated powders were annealed in ambient air while in-situ thermogravimetric analysis (TGA) and in-situ x-ray diffraction (XRD) data were acquired. The thermal stability of a series of Cu and Fe powder with different Al 2 O 3 thicknesses were determined with TGA. In both samples a clear shift in oxidation temperature is visible. For Cu and Fe powder coated with 25 nm Al 2 O 3 , we observed an increase of the oxidation temperature with 300-400°C. For the Cu powder a thin film of only 8 nm is required to obtain an initial increase in oxidation temperature of 200°C. In contrast, for Fe powder a thicker coating of 25 nm is required. In both cases, the oxidation temperature increases with increasing thickness of the Al 2 O 3 coating. These results illustrate that the Al 2 O 3 thin film, deposited by the thermal ALD process (TMA/H 2 O) can be an efficient and pinhole-free barrier layer for micrometer-sized powder particles, provided that the powder is properly agitated during the process to ensure sufficient vapour-solid interaction. |
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Wos |
000441492600108 |
Publication Date |
2018-06-25 |
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ISSN |
0257-8972 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.589 |
Times cited |
10 |
Open Access |
OpenAccess |
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Notes |
The authors acknowledge financial support from the Strategic Initiative Materials in Flanders (SIM, SBO-FUNC project) and the Special Research Fund BOF of Ghent University (GOA 01G01513). J. D. acknowledges the Research Foundation Flanders (FWO-Vlaanderen) for a postdoctoral fellowship. N.C. and S.B. acknowledge financial support from European Research Council (ERC Starting Grant 335078-COLOURATOMS). The authors acknowledge S. Goeteyn for the assistance in preliminary depositions. (ROMEO:green; preprint:; postprint:can ; pdfversion:cannot); ecas_sara |
Approved |
Most recent IF: 2.589 |
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Call Number |
EMAT @ emat @c:irua:152174UA @ admin @ c:irua:152174 |
Serial |
4994 |
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Author |
Kurttepeli, M.; Deng, S.; Verbruggen, S.W.; Guzzinati, G.; Cott, D.J.; Lenaerts, S.; Verbeeck, J.; Van Tendeloo, G.; Detavernier, C.; Bals, S. |
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Title |
Synthesis and characterization of photoreactive TiO2carbon nanosheet composites |
Type |
A1 Journal article |
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Year |
2014 |
Publication |
The journal of physical chemistry: C : nanomaterials and interfaces |
Abbreviated Journal |
J Phys Chem C |
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Volume |
118 |
Issue |
36 |
Pages |
21031-21037 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); Sustainable Energy, Air and Water Technology (DuEL) |
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Abstract |
We report the atomic layer deposition of titanium dioxide on carbon nanosheet templates and investigate the effects of postdeposition annealing in a helium environment using different characterization techniques. The crystallization of the titanium dioxide coating upon annealing is observed using in situ X-ray diffraction. The (micro)structural characterization of the films is carried out by scanning electron microscopy and advanced transmission electron microscopy techniques. Our study shows that the annealing of the atomic layer deposition processed and carbon nanosheets templated titanium dioxide layers in helium environment resulting in the formation of a porous, nanocrystalline and photocatalytically active titanium dioxide-carbon nanosheet composite film. Such composites are suitable for photocatalysis and dye-sensitized solar cells applications. |
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Place of Publication |
Washington, D.C. |
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Wos |
000341619500034 |
Publication Date |
2014-08-23 |
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ISSN |
1932-7447;1932-7455; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
4.536 |
Times cited |
9 |
Open Access |
OpenAccess |
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Notes |
This research was funded by the Flemish research foundation FWO-Vlaanderen, by the European Research Council (Starting Grant No. 239865) and by the Special Research Fund BOF of Ghent University (GOA-01G01513). G.G, M.K., J.V., S.B., and G.V.T. acknowledge funding from the European Research Council under the seventh Framework Program (FP7), ERC Starting Grant No. 278510 VORTEX and No. 335078 COLOURATOMS. ECASJO;; ECASSara; (ROMEO:white; preprint:; postprint:restricted 12 months embargo; pdfversion:cannot); |
Approved |
Most recent IF: 4.536; 2014 IF: 4.772 |
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Call Number |
UA @ lucian @ c:irua:119085 |
Serial |
3416 |
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