Correlation between optical, electrical and structural properties of vanadium dioxide thin films

Mlyuka, Nuru R.; Kivaisi, R.T.

doi:10.1007/s10853-006-0261-y

Cited by 22 publications

(11 citation statements)

References 15 publications

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“…Smaller grain size and larger amount of disorder have been reported for samples reactively sputtered at lower substrate temperatures. 3,20 We found similar tendency in our sputtering technique manifested by broader and weaker XRD lines of sample 1 versus sample 2 implying that sample 2 has better crystalline quality. Sample 3 was synthesized along with sample 2 but underwent thermal cycling during the XAS measurements.…”

Section: Resultssupporting

confidence: 72%

X-ray absorption spectroscopy of vanadium dioxide thin films across the phase-transition boundary

2007

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X-ray absorption spectroscopy ͑XAS͒ and x-ray photoemission spectroscopy of the V L edge and O K edge were performed on VO 2 thin films rf sputtered at various conditions. The spectra give evidence of the changes in the electronic structure depending on the film quality. XAS of the O K edge shows a decrease of the spacing between 3d and 3d bands by 0.8 eV with concurrent broadening of both bands for the sample sputtered at lower substrate temperature and consequently having more polycrystalline and disordered character. 3d band position appears to be more sensitive to the sample quality, indicating that the cation-ligand interaction is mostly affected likely due to the distortion of the local O coordination surrounding a V ion. The observed variation of the spectra in films of different morphologies may reflect the changes of the density of states responsible for the considerable variation of the metal-insulator transition ͑MIT͒ properties reported for VO 2 thin films synthesized at different conditions. The study of the temperature dependence of the XAS spectra including repeated measurements across the MIT revealed both reversible and irreversible V Ledge and O K-edge changes. The thermal cycling of the VO 2 films through the MIT shows irreversible shifts of the conduction bands toward lower photon energies apparently caused by the sample deterioration due to the lattice transformations at the MIT. The signature of a phase transition in a VO 2 film at MIT temperature ͑T MIT ͒ is clearly seen in the XAS O K-edge spectra which show reversible switches of the 3d and 3d bandwidths by approximately 20% depending on the sample being above or below T MIT .

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Section: Resultssupporting

confidence: 72%

X-ray absorption spectroscopy of vanadium dioxide thin films across the phase-transition boundary

2007

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“…We start with a 2D network of square VO 2 grains of differing size, each with total resistivity dependent on its size and its state (metal or insulator) 29,30 . The granularity of polycrystaline VO 2 is well documented 31,32 , although the size of grains may vary considerably from one VO 2 preparation to another. There is also evidence to suggest the percolation length scales for the IMT may not always coincide with the crystal granularity [33][34][35] .…”

Section: Grain-scale Model Of Oscillationsmentioning

confidence: 99%

Current oscillations in vanadium dioxide: Evidence for electrically triggered percolation avalanches

et al. 2012

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In this work, we experimentally and theoretically explore voltage controlled oscillations occurring in microbeams of vanadium dioxide. These oscillations are a result of the reversible insulator to metal phase transition in vanadium dioxide. Examining the structure of the observed oscillations in detail, we propose a modified percolative-avalanche model which allows for voltage-triggering. This model captures the periodicity and waveshape of the oscillations as well as several other key features. Importantly, our modeling shows that while temperature plays a critical role in the vanadium dioxide phase transition, electrically induced heating cannot act as the primary instigator of the oscillations in this configuration. This realization leads us to identify electric field as the most likely candidate for driving the phase transition.

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“…Modulation of the transmission of light by thin continuous films of VO 2 [8,9,[17][18][19] or by coatings of VO 2 nanoparticles [7,[20][21][22] has previously attracted the bulk of the attention in this field. In contrast, there have been fewer investigations [7,[23][24][25] into the use of VO 2 particles as opaque pigments in thermochromic paint systems.…”

Section: Introductionmentioning

confidence: 99%

The preparation of a plasmonically resonant VO₂thermochromic pigment

Bai¹,

Cortie²,

Maaroof³

et al. 2009

Nanotechnology

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Vanadium dioxide (VO(2)) undergoes a reversible metal-insulator transition, normally at approximately 68 degrees C. While the properties of continuous semi-transparent coatings of VO(2) are well known, there is far less information available concerning the potential use of discrete VO(2) nanoparticles as a thermochromic pigment in opaque coatings. Individual VO(2) nanoparticles undergo a localized plasmon resonance with near-infrared light at about 1100 nm and this resonance can be switched on and off by simply varying the temperature of the system. Therefore, incorporation of VO(2) nanoparticles into a coating system imbues the coating with the ability to self-adaptively modulate its own absorptive efficiency in the near-infrared. Here we examine the magnitude and control of this phenomenon. Prototype coatings are described, made using VO(2) powder produced by an improved process. The materials are characterized using calorimetry, x-ray diffraction, high-resolution scanning electron microscopy, transmission electron microscopy, and by measurement of optical properties.

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Correlation between optical, electrical and structural properties of vanadium dioxide thin films

Cited by 22 publications

References 15 publications

X-ray absorption spectroscopy of vanadium dioxide thin films across the phase-transition boundary

X-ray absorption spectroscopy of vanadium dioxide thin films across the phase-transition boundary

Current oscillations in vanadium dioxide: Evidence for electrically triggered percolation avalanches

The preparation of a plasmonically resonant VO₂thermochromic pigment

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Correlation between optical, electrical and structural properties of vanadium dioxide thin films

Cited by 22 publications

References 15 publications

X-ray absorption spectroscopy of vanadium dioxide thin films across the phase-transition boundary

X-ray absorption spectroscopy of vanadium dioxide thin films across the phase-transition boundary

Current oscillations in vanadium dioxide: Evidence for electrically triggered percolation avalanches

The preparation of a plasmonically resonant VO2thermochromic pigment

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The preparation of a plasmonically resonant VO₂thermochromic pigment