Photocatalytic efficiency of TiO2/SnO2 thin film stacks prepared by DC magnetron sputtering

Kanai, N.; Nuida, Tomohiro; Ueta, Keiichi; Hashimoto, Kazuhito; Watanabe, Toshiya; Ohsaki, Hisashi

doi:10.1016/j.vacuum.2004.01.056

Cited by 54 publications

(16 citation statements)

References 10 publications

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“…It has also been reported that the photo-generated carriers in the TiO 2 film play a key role in photocatalytic reactions. 9,20) Figures 9(a) and (b) show the electron transfer paths before and after the TiO 2 and SnO 2 films are combined. The quantity of electrons on the surface is increased by the transfer of electrons from TiO 2 to SnO 2 .…”

Section: Resultsmentioning

confidence: 99%

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Enhancing the Sensitivity of Oxygen Sensors through the Photocatalytic Effect of SnO2/TiO2 Film

Lee

Hwang

2005

Mater. Trans.

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This paper investigates the effect of photocatalysis on the sensitivity of oxygen sensors constructed with SnO 2 /TiO 2 thin films. An R.F. magnetron sputtering system is employed to fabricate SnO 2 /TiO 2 double-layer films. The thin films are deposited with SnO 2 /TiO 2 thickness ratios of 250/50, 200/100, 150/150, 100/200, and 50/250 nm, respectively. During deposition, the Ar:O 2 flow rate is fixed at 4:1. To stabilize the material properties, the films are annealed for four hours at a temperature of either 550 or 650 C. The increase in sensitivity of the SnO 2 / TiO 2 thin films when irradiated by UV light with a wavelength of 365 nm is investigated. The results indicate that the annealed samples have higher oxygen sensitivities than the as-deposited samples. The sensitivity of the non-annealed samples increases from 0.70 to 1.15 under UV irradiation, while the sensitivity of the annealed samples increases from 7.17 to 10.60. Therefore, it is clear that UV irradiation causes the sensitivity of the SnO 2 /TiO 2 thin films to increase significantly. Finally, it is found that the oxygen sensitivity of the SnO 2 /TiO 2 thin films increases as the SnO 2 /TiO 2 ratio is reduced.

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Section: Resultsmentioning

confidence: 99%

“…However, these double-layer films have only seldom been employed for gas sensor applications. 5,[8][9][10] This study employs the R.F. sputtering technique to prepare various SnO 2 /TiO 2 double-layer thin films.…”

Section: Introductionmentioning

confidence: 99%

Enhancing the Sensitivity of Oxygen Sensors through the Photocatalytic Effect of SnO2/TiO2 Film

Lee

Hwang

2005

Mater. Trans.

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“…The combination of SnO 2 and TiO 2 has been widely used in solar cells 13,14) and photocatalysts, 15,16) but it is not commonly used in gas sensors, especially not when combined in a double layer structure. Theoretically, the conduction band of SnO 2 is lower than that of TiO 2 , causing electrons to pass from TiO 2 to SnO 2 when the double-layer film is formed.…”

Section: )mentioning

confidence: 99%

Characterization of SnO2/TiO2 Double-Layer Films as Alcohol Sensing Materials

et al. 2004

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The aim of this study is to improve the sensitivity of alcohol sensors by combining the advantages of TiO 2 and SnO 2 films in a double layer device. In this study, an RF magnetron sputtering system was employed to fabricate SnO 2 /TiO 2 double-layer and SnO 2 single-layer films for applications as alcohol sensors.The TiO 2 layer of the SnO 2 /TiO 2 double-layer thin film and the SnO 2 single-layer film were all deposited under various O 2 /Ar ratios of 0.2, 0.4, 0.6, and 0.8. The SnO 2 layer, the top coating of SnO 2 /TiO 2 double-layer, was deposited at a fixed O 2 /Ar ratio of 0.2 with an argon flow rate of 50 sccm. The crystal structure and surface morphology of the films were examined by X-ray diffraction (XRD), Grazing Incident X-Ray Diffraction (GID) and Scanning Electron Microscopy (SEM). The sensitivity value of the film can be calculated from the change in the resistance of the film when exposed to alcohol.The results show that SnO 2 /TiO 2 double layer films have better sensitivity and quicker recovery time compared to those of single-layer SnO 2 films.

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“…Another reason is that the conduction type of the metal oxide is determined by grain size. When the grain size (D) is small enough (D<2L, where L is the spacecharge depth), the metal oxide resistivity is determined by grain control, and the conduction becomes a surface conduction [34][35][36][37][38][39][40][41][42].…”

Section: Introductionmentioning

confidence: 99%

Nanostructured TiO2-based mixed metal oxides prepared using microemulsions for carbon monoxide detection

et al. 2007

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Nanostructured powders of Nb-doped TiO2 (TN) and SnO2 mixed with Nb-doped TiO2 in two different atomic ratios-10 to 1 (TSN 101) and 1 to 1 (TSN 11)-were synthesized using the reverse micelle microemulsion of a nonionic surfactant (brine solution/1-hexanol/Triton X-100/cyclohexane). The powders were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Thick films were fabricated for gas sensors and characterized by XRD analysis and field emission scanning electron microscopy (FE-SEM). The effects of the film morphology and firing temperature in the range 650-850 °C on CO sensitivity were studied. The best gas response, expressed as the ratio between the resistance in air and the resistance under gas exposure (R air/R gas), was measured for TSN 11 at 11 for 1,000 ppm CO exposure. All types of sensors showed good thermal stability. The electrochemical impedance spectroscopy (EIS) measurements were performed in different gas atmospheres (air, O2, CO and NO 2) to better understand the electrical properties of the nanostructured mixed metal oxides. © 2007 Springer Science+Business Media, LLC

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Photocatalytic efficiency of TiO2/SnO2 thin film stacks prepared by DC magnetron sputtering

Cited by 54 publications

References 10 publications

Enhancing the Sensitivity of Oxygen Sensors through the Photocatalytic Effect of SnO<SUB>2</SUB>/TiO<SUB>2</SUB> Film

Enhancing the Sensitivity of Oxygen Sensors through the Photocatalytic Effect of SnO<SUB>2</SUB>/TiO<SUB>2</SUB> Film

Characterization of SnO<sub>2</sub>/TiO<sub>2</sub> Double-Layer Films as Alcohol Sensing Materials

Nanostructured TiO2-based mixed metal oxides prepared using microemulsions for carbon monoxide detection

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