Design of thin-film configuration of SnO2–Ag2O composites for NO2 gas-sensing applications

In this study, a two-layered thin-film structure consisting of a dispersed nanoscaled Ag O phase and SnO layer (SA) and a mono-composite film layer (CSA) consisting of a nanoscale Ag O phase in the SnO matrix are designed and fabricated for NO gas sensor applications. Two-layered and mono-layered Sn...

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Bibliographic Details
Published in:Nanotechnology reviews (Berlin) 2022-05, Vol.11 (1), p.1842-1853
Main Authors: Liang, Yuan-Chang, Hsu, Yu-Wei
Format: Article
Language:English
Subjects:
Configuration management
Dynamic response
Electrical junctions
Gas sensors
gas-sensing
microstructure
Nitrogen dioxide
P-n junctions
Sensors
Sputtering
Thin films
thin-film configuration
Tin dioxide
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Summary:In this study, a two-layered thin-film structure consisting of a dispersed nanoscaled Ag O phase and SnO layer (SA) and a mono-composite film layer (CSA) consisting of a nanoscale Ag O phase in the SnO matrix are designed and fabricated for NO gas sensor applications. Two-layered and mono-layered SnO –Ag O composite thin films were synthesized using two-step SnO and Ag O sputtering processes and Ag O/SnO co-sputtering approach, respectively. In NO gas-sensing measurement results, both SA and CSA thin films that functionalized with an appropriate Ag O content exhibit enhanced gas-sensing responses toward low-concentration NO gas in comparison with that of pristine SnO thin film. In particular, a gas sensor made from the mono-composite SnO –Ag O layer demonstrates apparently higher NO gas-sensing performance than that of double-layered SnO –Ag O thin-film sensor. This is attributed to substantially numerous p–n junctions of Ag O/SnO formed in the top region of the SnO matrix. The gas-sensing response of the optimal sample (CSA270) toward 10 ppm NO gas is 5.91, and the response/recovery speeds in a single cycle dynamic response plot are 28 s/168 s toward 10 ppm NO , respectively. Such a p–n thin-film configuration is beneficial to induce large electric resistance variation before and after the introduction of NO target gas during gas-sensing tests. The experimental results herein demonstrate that the gas-sensing performance of p–n oxide composite thin films can be tuned the appropriate design of composite thin-film configuration.
ISSN:2191-9089
2191-9097
DOI:10.1515/ntrev-2022-0111