We are experiencing minor difficulties with some of our submission forms, which we are working to resolve. You should still be able to submit items, but if you have any issues while submitting, please contact us at dspace-lib@mit.edu.

Toxic gas sensors using thin film transistor platform at low temperature

Thumbnail Image
Download
Name

428091372-MIT.pdf

Description
Full printable version
Size

47.29 MB

Format

Adobe PDF

Checksum (MD5)

66e38a0e96e7127efc4392cf886023a7

Author(s)
Jin, Yoonsil
Advisor(s)
Harry L. Tuller.
Date Issued
2009
Publisher
Massachusetts Institute of Technology
Abstract
Semiconducting metal-oxides such as SnO₂, TiO₂, ZnO and WO₃ are commonly used for gas sensing in the form of thin film resistors (TFRs) given their high sensitivity to many vapor species, simple construction and capability for miniaturization. Furthermore, they are generally more stable than polymer-based gas sensors. However, unlike polymers, metal oxide gas sensors must typically be operated between 200-400°C to insure rapid kinetics. Another problem impacting TFR performance and reproducibility is related to poorly understood substrate-semiconductor film interactions. Space charges at this heterojunction are believed to influence chemisorption on the semiconductor-gas interface, but unfortunately, in an unpredictable manner. In this study, the feasibility of employing illumination and the thin film transistor (TFT) platform as a means of reducing operation temperature was investigated on ZnO based TFTs for gas sensors applications. Response to NO₂ is observed at significantly reduced temperature. Photoconductivity measurements, performed as a function of temperature on ZnO based TFRs, indicate that this results in a photon-induced desorption process. Also, transient changes in TFT channel conductance and transistor threshold voltage are obtained with application of gate bias, suggesting that TFTs offer additional control over chemisorption at the semiconductor-gas interface.
Description
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2009.
Includes bibliographical references (leaves [71-73]).
Subjects
Materials Science and Engineering.
MIT Department
Massachusetts Institute of Technology. Department of Materials Science and Engineering
Terms of Use
M.I.T. theses are protected by
copyright. They may be viewed from this source for any purpose, but
reproduction or distribution in any format is prohibited without written
permission. See provided URL for inquiries about permission.
Persistent DSpace Link
PrivacyPermissionsAccessibilityContact us
Notify us about copyright concerns.