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Different materials are studied for environmental gas sensors as well as photodetection prototypes. A ZnO/MoS2 p-n junction was synthetized to act as a multifunctional sensor prototype. After the ZnO was prepared on a silicon substrate by using DC sputtering at room temperature, molybdenum disulfide layers were spin-coated on a nanostructured zinc oxide flake-shaped surface to form an active layer. The heterostructure’s composite surface was examined using scanning electron microscopy, energy-dispersed X-ray, and Raman spectroscopy. Responses to light frequencies, light intensities, and gas chemical tracing were characterized, revealing an enhanced multifunctional performance of the prototype. Characterizations of light-induced photocurrents indicted that the obtained response strength (photocurrent/illumination light power) was up to 0.01 A/W, and the response time was less than 5 ms. In contrast, the gas-sensing measurements showed that its response strength (variation in resistance/original resistance) was up to 3.7% and the response time was down to 150 s when the prototype was exposed to ammonia gas, with the concentration down to 168 ppm. The fabricated prototype appears to have high stability and reproducibility, quick response and recovery times, as well as a high signal-to-noise ratio.
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Nanostructured Diamond Composites for Multifunctional Sensing Applications
We report studies of multifunctional, nanostructured diamond composites that were fabricated using chemical vapor deposition (CVD) techniques. Grain sizes from micrometer, to submicron, nano, and ultrananocrystalline diamond (UNCD) were controlled by varying CH4, hydrogen, and argon gas concentrations during the syntheses. Scanning electron microscopy (SEM) and Raman scattering spectroscopy were used to investigate the morphologies, composites, and crystallinities of the films. Four multifunctional sensor prototypes were designed, fabricated, and tested, based on the four diamond materials of different grain sizes. The responses of the four prototypes to either pollution gas or UV light illumination were systematically investigated at different operating temperatures. Experimental data indicated the obtained UNCD composite from the low-cost simple CVD fabrication technique appeared to have very good sensitivities when exposed to low concentrations of H2 or NH3 gas with a decent response and fast recovery time. Furthermore, highly induced photocurrents from both microdiamond- and UNCD-based prototypes to deep UV illumination were also demonstrated, with responsivities up to 2750 mA/W and 550 mA/W at 250 nm wavelength, respectively. Overall, the fabricated UNCD prototypes displayed a good balance in performance for multifunctional sensor applications in terms of responsivity, stability, and repeatability.
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- Award ID(s):
- 1736093
- PAR ID:
- 10497623
- Publisher / Repository:
- MDPI
- Date Published:
- Journal Name:
- Chemosensors
- Volume:
- 10
- Issue:
- 11
- ISSN:
- 2227-9040
- Page Range / eLocation ID:
- 488
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3390/chemosensors10110488
