Optical and electrical switching in nanostructured coatings of VO <inf>2</inf>

Gentle, AR; Maaroof, AI; Cortie, MB; Smith, GB

Optical and electrical switching in nanostructured coatings of VO <inf>2</inf>

Gentle, AR

Maaroof, AI Cortie, MB

Smith, GB

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Publication Type:: Conference Proceeding
Citation:: Proceedings of SPIE - The International Society for Optical Engineering, 2007, 6647
Issue Date:: 2007-12-01

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Field	Value	Language
dc.contributor.author	Gentle, AR https://orcid.org/0000-0001-8964-0722	en_US
dc.contributor.author	Maaroof, AI	en_US
dc.contributor.author	Cortie, MB https://orcid.org/0000-0003-3202-6398	en_US
dc.contributor.author	Smith, GB https://orcid.org/0000-0002-6985-2880	en_US
dc.date.issued	2007-12-01	en_US
dc.identifier.citation	Proceedings of SPIE - The International Society for Optical Engineering, 2007, 6647	en_US
dc.identifier.isbn	9780819467959	en_US
dc.identifier.issn	0277-786X	en_US
dc.identifier.uri	http://hdl.handle.net/10453/788
dc.description.abstract	Vanadium dioxide undergoes a reversible metal-insulator phase transition at about 68°C. Coatings of this compound are reflective in the infrared above this temperature, and transmissive or absorptive below it, while resistivity changes by several orders of magnitude. We present a convenient method for depositing films with nano-size grains, which are then optically and electrically characterised. Emphasis in this study is the impact of aluminum doping and grain structure. The optical hysteresis is presented and its switching range is not altered at different doping levels but the value of transition temperature Tc does shift. In contrast hysteresis in dc resistance does change with a strong correlation between the fall in resistance in the semiconductor state with doping, the drop in Tc and the electrical properties in the metal state. For grain sizes under about 180 nm the conductivity in the metal phase is not linear in temperature but is thermally activated, with activation energies AE dependent on both grain size G and doping level. Simple mathematical relationships are found connecting ΔE with G and with carrier density in the semiconductor state. ΔE ranges in our samples from 0.15 eV in the smallest grain sizes to around 0.06 eV. This anomalous low frequency metal response is linked to excitations that arise in the metal phase associated with transient singlet pairing on neighbouring sites. Such pairing is weakened by doping, and in large grains appears to be present but incoherent.	en_US
dc.relation.ispartof	Proceedings of SPIE - The International Society for Optical Engineering	en_US
dc.relation.isbasedon	10.1117/12.733200	en_US
dc.title	Optical and electrical switching in nanostructured coatings of VO <inf>2</inf>	en_US
dc.type	Conference Proceeding
utslib.citation.volume	6647	en_US
utslib.for	1007 Nanotechnology	en_US
dc.location.activity	San Diego, California, USA	en_US
dc.location.activity	San Diego, CA
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Faculty of Science/School of Mathematical and Physical Sciences
utslib.copyright.status	closed_access
pubs.publication-status	Published	en_US
pubs.volume	6647	en_US

Abstract:

Vanadium dioxide undergoes a reversible metal-insulator phase transition at about 68°C. Coatings of this compound are reflective in the infrared above this temperature, and transmissive or absorptive below it, while resistivity changes by several orders of magnitude. We present a convenient method for depositing films with nano-size grains, which are then optically and electrically characterised. Emphasis in this study is the impact of aluminum doping and grain structure. The optical hysteresis is presented and its switching range is not altered at different doping levels but the value of transition temperature Tc does shift. In contrast hysteresis in dc resistance does change with a strong correlation between the fall in resistance in the semiconductor state with doping, the drop in Tc and the electrical properties in the metal state. For grain sizes under about 180 nm the conductivity in the metal phase is not linear in temperature but is thermally activated, with activation energies AE dependent on both grain size G and doping level. Simple mathematical relationships are found connecting ΔE with G and with carrier density in the semiconductor state. ΔE ranges in our samples from 0.15 eV in the smallest grain sizes to around 0.06 eV. This anomalous low frequency metal response is linked to excitations that arise in the metal phase associated with transient singlet pairing on neighbouring sites. Such pairing is weakened by doping, and in large grains appears to be present but incoherent.

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http://hdl.handle.net/10453/788