Frequency And Percolation Dependence Of The Observed Phase Transition In Nanostructured And Doped Vo2 Thin Films

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Show simple item record Gentle, Angus en_US Maaroof, Abbas en_US Smith, Geoff en_US
dc.contributor.editor en_US 2010-05-28T09:49:33Z 2010-05-28T09:49:33Z 2009 en_US
dc.identifier 2009002394 en_US
dc.identifier.citation Gentle Angus, Smith Geoffrey, and Maaroof Abbas 2009, 'Frequency And Percolation Dependence Of The Observed Phase Transition In Nanostructured And Doped Vo2 Thin Films', Spie-Soc Photoptical Instrumentation Engineers, vol. 3, no. 031505, pp. 1-15. en_US
dc.identifier.issn 1934-2608 en_US
dc.identifier.other C1 en_US
dc.description.abstract The response to applied electric fields of vanadium dioxide thin films above and below the phase transition depends on the size of grains if below ~200nm across, and on aluminum doping above a critical concentration. Tc drops as doping level increases, but does not depend on grain size. The observed phase transition undergoes a remarkable qualitative shift as the applied field goes from optical to low frequencies. The expected insulator to metal transition is found at optical frequencies, but at low frequencies an insulator-to-insulator transition occurs. Optical switching at both T < Tc and T > Tc is nearly independent of doping level and grain size. In contrast dc properties in both phases are sensitive to both factors. The band gaps from optical and dc data differ, and densities of states change with doping level. Such behaviour can arise if there is a transient phase change. The way doping and grain size can support such a phase is discussed. Only individual nanograins need to switch phases coherently to explain data, not the whole sample. Resistance as a function of composition across the transition was derived using effective medium compositional analysis of optical data in the hysteresis zone. The percolation thresholds are not at the usual Tc values. en_US
dc.language en_US
dc.publisher Spie-Soc Photoptical Instrumentation Engineers en_US
dc.rights Copyright 2009. Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic electronic or print reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes en_US
dc.title Frequency And Percolation Dependence Of The Observed Phase Transition In Nanostructured And Doped Vo2 Thin Films en_US
dc.parent Journal of Nanophotonics en_US
dc.journal.volume 3 en_US
dc.journal.number 031505 en_US
dc.publocation United States en_US
dc.identifier.startpage 1 en_US
dc.identifier.endpage 15 en_US SCI.Faculty of Science en_US
dc.conference Verified OK en_US
dc.for 100711 en_US
dc.personcode 000307 en_US
dc.personcode 730312 en_US
dc.personcode 010727 en_US
dc.percentage 100 en_US Nanophotonics en_US
dc.classification.type FOR-08 en_US
dc.edition en_US
dc.custom en_US en_US
dc.location.activity ISI:000272328600006 en_US
dc.description.keywords NA en_US
dc.staffid en_US
dc.staffid 010727 en_US

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