Thin Films of Tungsten Disulfide Grown by Sulfurization of Sputtered Metal for Ultra-Low Detection of Nitrogen Dioxide Gas
Tungsten disulfide (WS<sub>2</sub>) is attractive for the development of chemiresistive sensors due to its favorable band gap, as well as its mechanical strength and chemical stability. In this work, we elaborate a procedure for the synthesis of thin films consisting of vertically and/or...
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| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-04-01
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| Series: | Nanomaterials |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2079-4991/15/8/594 |
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| Summary: | Tungsten disulfide (WS<sub>2</sub>) is attractive for the development of chemiresistive sensors due to its favorable band gap, as well as its mechanical strength and chemical stability. In this work, we elaborate a procedure for the synthesis of thin films consisting of vertically and/or horizontally oriented WS<sub>2</sub> nanoparticles by sulfurizing nanometer-thick tungsten layers deposited on oxidized silicon substrates using magnetron sputtering. According to X-ray photoelectron spectroscopy and Raman scattering data, WS<sub>2</sub> films grown in an H<sub>2</sub>-containing atmosphere at 1000 °C are almost free of tungsten oxide. The WS<sub>2</sub> film’s thickness is controlled by varying the tungsten sputtering duration from 10 to 90 s. The highest response to nitrogen dioxide (NO<sub>2</sub>) at room temperature was demonstrated by the film obtained using a tungsten layer sputtered for 30 s. The increased sensitivity is attributed to the high surface-to-volume ratio provided by the horizontal and vertical orientation of the small WS<sub>2</sub> nanoparticles. Based on density functional calculations, we conclude that the small in-plane size of WS<sub>2</sub> provides many high-energy sites for NO<sub>2</sub> adsorption, which leads to greater charge transfer in the sensor. The detection limit of NO<sub>2</sub> calculated for the best sensor (WS<sub>2</sub>-30s) is 15 ppb at room temperature and 8 ppb at 125 °C. The sensor can operate in a humid environment and is significantly less sensitive to NH<sub>3</sub> and a mixture of H<sub>2</sub>, CO, and CO<sub>2</sub> gases. |
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| ISSN: | 2079-4991 |