Characterization of pulsed laser deposited WO3 thin films for electrochromic devices

Rougier, Aline; Portemer, F.; Quédé, A.; Marssi, M. El

doi:10.1016/s0169-4332(99)00335-9

Cited by 274 publications

(202 citation statements)

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“…Such a presence of water contamination was also reported by Nguyen et al [10]. Another weak band at 1435 cm -1 have been assigned to the stretching vibration of NH 4 due to contamination with ambient atmosphere [11] Fig 4. shows the optical transmittance spectra of WO 3 films deposited at room temperature with different substrate bias voltages. The optical transmittance of all the films is above 80% in the visible region.…”

Section: Resultssupporting

confidence: 75%

“…The transmittance slightly decreases as the substrate bias voltage increase. The optical absorption edge was shifted to higher wavelength with increase of substrate bias voltage from 0 to -150 V. The fundamental absorption edge of WO 3 films is formed by non-direct permitted transition of the 2p electron from the valance band of the oxygen to the 5d condition bands of tungsten [11]. The optical absorption coefficient ( ) of the films was calculated from the optical transmittance (T) data where the reflection losses were taken into account.…”

Section: Resultsmentioning

confidence: 99%

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Influence of substrate bias voltage on structural and optical properties of RF reactive magnetron sputtered WO₃thin films

Madhavi

Kondaiah

Uthanna

2012

J. Phys.: Conf. Ser.

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Abstract. In this investigation, tungsten oxide (WO 3 ) thin films have been deposited on unheated glass substrates by RF magnetron sputtering of tungsten target at constant oxygen partial pressure of 6x10 -2 Pa, sputtering power of 150 W and at different substrate bias voltages in the range from 0 to -150 V. The structural and optical properties of the films were investigated by using X-ray diffraction, Fourier transform infrared spectroscopy and UV-Vis-NIR spectrophotometers. The films formed up to substrate bias voltage of -50 V were found to be amorphous in nature, while those films formed at -100 V showed a weak (200) reflection indicates the presence of monoclinic phase of WO 3 in amorphous matrix. The optical transmittance of the films was in the range 78 -95 % in the wavelength range of 500 -1200 nm. The absorption band edge was shifted towards higher wavelength side with increasing substrate bias voltage. The optical band gap of the films decrease from 2.81 to 2.69 eV with increase of substrate bias voltage from 0 to -150 V respectively. The refractive index of the films increased from 2.19 to 2.27 with increase of substrate bias voltage from 0 to -150 V respectively. Introduction:In recent past, tungsten oxide (WO 3 ) has been extensively studied for its distinctive physical and chemical properties especially the electrochromic, photochromic, gas sensors properties. Electro chromism in amorphous tungsten oxide films has been extensively studied since it was discovered in 1961. The improvement of material properties requires a closer inspection of preparation conditions. Various techniques such as thermal evaporation The chemical composition, microstructure and physical behaviour of the deposited films relies more on the control of deposition parameters such as substrate temperature, gas pressures, sputtering power and substrate bias voltage. The primary purpose of biasing is to prevent the deposited film from becoming contaminated with gas atoms and other gas/metal reaction products. A negative potential applied to the substrate vary the ion energy, and further influence the nucleation and growth kinetics of the films. Subsequently, the microstructure and physical properties of the films are greatly modified. The present study is aimed to investigate the influence of substrate bias voltage on the growth characteristics of RF reactive magnetron sputtered WO 3 films.

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Section: Resultssupporting

confidence: 75%

Section: Resultsmentioning

confidence: 99%

Influence of substrate bias voltage on structural and optical properties of RF reactive magnetron sputtered WO₃thin films

Madhavi

Kondaiah

Uthanna

2012

J. Phys.: Conf. Ser.

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“…The modes appeared in the low-frequency region (260 cm −1 , 321 cm −1 ) are due to the bending vibration of δ (W 6+ -O), and the mode presented at the high -frequency (801 cm −1 ) region can be assigned to the stretching vibration of ν (W 6+ -O). [31][32][33] The intensities of the vibrational modes related to WO 3 increased with a rise in deposition temperature from 400 • C -600 • C and diminish at 800 • C, which indicates the formation of pure BWO phase. Furthermore, the full width at half maximum of the peak improves with an increase in deposition temperature.…”

Section: Resultsmentioning

confidence: 98%

Irreversible thermochromic response of RF sputtered nanocrystalline BaWO4 films for smart window applications

Kumar

Pamu

2015

AIP Advances

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We report irreversible thermochromic behaviour of BaWO 4 (BWO) films for the first time. BWO films have been deposited at different substrate temperatures (RT, 200, 400, 600 and 800 • C) using RF magnetron sputtering in pure argon plasma. BWO films deposited at 800 • C exhibit crystalline nature. Also, BWO films deposited in the temperature range of 400 -600 • C exhibit WO 3 as a secondary phase and its weight percentage decreases with an increase in deposition temperature, whereas the films deposited at 800 • C exhibited pure tetragonal phase. FESEM images revealed that as the average particle sizes of the films are higher as compared with the thickness of the films and is explained based on Avrami type nucleation and growth. The transmittance of the films decreases with an increase in deposition temperature up to 600 • C and increases thereafter. Films deposited at 600 • C show ≤ 20% transmittance, looking at the films deposited at room temperature and 800 • C exhibits 90 and 70%, respectively. The refractive index and extinction coefficient of the films show profound dependence on crystallinity and packing density. The optical bandgap of BWO films increases significantly with an increase in O 2 % during the deposition. The optical bandgap of the BWO films deposited at different temperatures in pure argon plasma, are in the range of 3.7 to 3.94 eV whereas the films deposited at 600 • C under different O 2 plasma are in the range of 3.6 -4.5 eV. The formations of colour centres are associated with the oxygen vacancies, which are clearly seen from the optical bandgap studies. The observed irreversible thermochromic behaviour in BWO films is attributed to the presence of oxygen vacancies that arises due to the electrons trapped at oxygen vacancies causing an inter valence charge transfer of W 5+ to W 6+ and is confirmed through the change in the optical density (∆OD). Further, the Raman spectra are being used to quantify the presence of oxygen vacancies and the formation of pure BWO phase. The obtained optical responses of BWO films are promising for solar cell and smart window applications. C 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License. [http://dx

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“…polythiophene, polypyrrole), WO 3 is often regarded as a more promising candidate material, due to its transparency and good reversibility in colour change when an external electrical field is applied [2,3] and is the most widely used and most cited cathodically-colouring material in the patent literature. Various methods have been developed to synthesise tungsten oxide films (TOFs), including laser ablation [4], anodic oxidation [5], sputtering [6], and electrodeposition [7]. Compared with these methods, sol-gel processing is an inexpensive, simple and controllable alternative, facilitating the bespoke engineering of a variety of nanostructures.…”

Section: Introductionmentioning

confidence: 99%

Preparation, characterisation and electrochromic property of mesostructured tungsten oxide films via a surfactant templated sol–gel process from tungstic acid

Wang

Pang

Hodgson

2010

J Sol-Gel Sci Technol

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Characterization of pulsed laser deposited WO3 thin films for electrochromic devices

Cited by 274 publications

References 23 publications

Influence of substrate bias voltage on structural and optical properties of RF reactive magnetron sputtered WO₃thin films

Influence of substrate bias voltage on structural and optical properties of RF reactive magnetron sputtered WO₃thin films

Irreversible thermochromic response of RF sputtered nanocrystalline BaWO4 films for smart window applications

Preparation, characterisation and electrochromic property of mesostructured tungsten oxide films via a surfactant templated sol–gel process from tungstic acid

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Characterization of pulsed laser deposited WO3 thin films for electrochromic devices

Cited by 274 publications

References 23 publications

Influence of substrate bias voltage on structural and optical properties of RF reactive magnetron sputtered WO3thin films

Influence of substrate bias voltage on structural and optical properties of RF reactive magnetron sputtered WO3thin films

Irreversible thermochromic response of RF sputtered nanocrystalline BaWO4 films for smart window applications

Preparation, characterisation and electrochromic property of mesostructured tungsten oxide films via a surfactant templated sol–gel process from tungstic acid

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Influence of substrate bias voltage on structural and optical properties of RF reactive magnetron sputtered WO₃thin films

Influence of substrate bias voltage on structural and optical properties of RF reactive magnetron sputtered WO₃thin films