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Micromachined Array Studies of Tin Oxide Films: Nucleation, Structure and Gas Sensing Characteristics

Published online by Cambridge University Press:  10 February 2011

B. Panchapakesan
Affiliation:
Maryland MEMS Laboratory, Department of Mechanical Engineering & The Institute for Systems Research, University of Maryland, College Park, MD 20742
D. L. DeVoe
Affiliation:
Maryland MEMS Laboratory, Department of Mechanical Engineering & The Institute for Systems Research, University of Maryland, College Park, MD 20742
R. E. Cavicchi
Affiliation:
Chemical Science and Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899
R. M. Walton
Affiliation:
Chemical Science and Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899
S. Semancik
Affiliation:
Chemical Science and Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899
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Abstract

The ability to fabricate sensitive and stable gas sensors which can detect low concentrations of gaseous species is necessary for many critical applications such as environmental safety monitoring. Although highly sensitive gas sensors have been produced by dispersion of catalytic metals on oxide sensing films, fouling of catalysts can cause instability in sensor performance. We have examined an approach which involves fine tuning the microstructure of tin oxide sensing films by vapor depositing an ultra-thin film of seed layer metals prior to tin oxide deposition. Metals including Fe, Sn and Pt have been investigated for their influence on tin oxide growth. Systematic studies of the growth mechanism and microstructure of CVD tin oxide using four-element arrays of “microhotplates” have revealed a number of different film morphologies which result from seeding. Enhancements in sensitivity for seeded growth relative to unseeded growth suggest a method of producing sensitive gas sensors which may not require the addition of surface catalytic layers. In this study we also demonstrate the use of microhotplates not only as sensing devices, but as excellent platforms for materials research.

Type
Research Article
Copyright
Copyright © Materials Research Society 1999

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References

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