structural and optical properties of pulsed laser deposited v 2 o 5 thin f ilms apr 20 th, 2009 thin...
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![Page 1: Structural and optical properties of pulsed laser deposited V 2 O 5 thin f ilms Apr 20 th, 2009 Thin film class Paper reading session Presentation by Jiajia](https://reader030.vdocuments.net/reader030/viewer/2022032600/56649daa5503460f94a9785e/html5/thumbnails/1.jpg)
Structural and optical properties of pulsed laser deposited V2O5 thin films
Apr 20th, 2009
Thin film class Paper reading session
Presentation by Jiajia Tan
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OutlineApplication of V2O5
Research Motivation and objective
Experimental procedure PLDCharacterization 1. XRD 2. XPS 3. Transmittance measurement 4. TEM
Important results
Conclusions
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Application
Mainly:
Optical switching devices
Electrochromic devices
Cathodes materials for Li Battaries
Structure:
Orthorhombic unit cell
Layer-like structure
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ObjectiveV2O5 thin films deposited by PLD
on amorphous glass
at 13.33 Pa and 220℃
at various laser fluence and pulse numbers.
MotivationVanadium oxide is a good catalyst,
especially when its size reaches nanoscale.
--->
The formation of nanoclusters.
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Target:
1, Hhigh purity V2O3 powders are pressed to pallets;
2, V2O3 changes to V2O5 after annealed at 550 in air for 24℃ h.
Laser parameters:
*Pulsed ArF excimer laser (λ=193 nm,pulse duration 15 ns at FWHM)
at a fluence level of 0.9–2.7 J/cm2.
*Repetition rate was 2 Hz.
Experiment procedure: PLD
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Experimental conditions
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Important results
The size of NCs is in the range of 2–40 nm. From experimental results it is evident that NC size depends on the laser fluence used during deposition.
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The optical band gap is about 2.52 eV.
Eghn )/1(^
T decreases at higher frequency.
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Why?Quantum confinement effect give rise to the energy gap
Eg (film) = 2.52 eV > Eg (bulk) =2.25 eV.
In the range of 2–40 nm.
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Conclusion
Structure:
Range from 2–40 nm.
NC size can be selected by adjusting the laser fluence.
Optical properties:
Aabsorption edge is about 2.52 eV.
Bohr radius is calculated to 4.52 nm.
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Bohr radius:The physical properties change due to quantum confinement that results from electrons and holes being squeezed into a dimension that approaches a critical quantum measurement, called the exciton Bohr radius.