NDLI: Operating temperature effect in WO films for gas sensing

Content Provider	IEEE Xplore Digital Library
Author	Govender, M. Motaung, D.E. Mwakikunga, B.W. Umapathy, S. Sil, S. Prasad, A.K. Machatine, A.G.J. Kunert, H.W.
Copyright Year	2013
Description	Author affiliation: DST, Council for Sci. & Ind. Res., Tshwane, South Africa (Govender, M.; Motaung, D.E.; Mwakikunga, B.W.) \|\| Surface & Nanosci. Div., Indira Gandhi Centre for Atomic Res., Kalpakkam, India (Prasad, A.K.) \|\| Sch. of Phys., Univ. of Pretoria, Pretoria, South Africa (Machatine, A.G.J.; Kunert, H.W.) \|\| Dept. of Inorg. & Phys. Chem., Indian Inst. of Sci., Bangalore, India (Umapathy, S.; Sil, S.)
Abstract	$WO_{3}$ film sputtered on $Al_{2}O_{3}$ was used to sense ppm concentrations of $NO_{2}$ and $NH_{3}$ gas. The optimum working temperature of the amorphous film was found to be 200°C for both the gases, in accordance with literature. However, thermo-gravimetric analysis of the films predicts a different mechanism from that in literature which speculates that there is loss of water molecules from $WO_{3}$ at 200°C and therefore better sensing response. Thermo-gravimetric analysis shows that there is an increase in weight percentage in air at 200°C, which we speculate to be due to optimum surface oxygen content which leads to better sensing response. Raman spectroscopy at 200°C supports our speculation by showing no structural change in the $WO_{3}$ compound and no shifting of the ~700 $cm^{1}$ peak which is indicative of water loss. Furthermore, there was a marked change in the heating-cooling hysteresis at 200°C, which could result from the optimum surface oxygen content changing the electron transport properties The 200°C may also be regarded as a new transition temperature in $WO_{3}$ although the transition is not structural (electron-phonon coupling) but is electronic in nature (electron-electron correlation) and this transition temperature could be linked to the optimum sensing temperature of $WO_{3}.$
Starting Page	1
Ending Page	4
File Size	1290830
Page Count	4
File Format	PDF
ISBN	9781467346429
ISSN	19300395
DOI	10.1109/ICSENS.2013.6688192
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2013-11-03
Publisher Place	USA
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Films Temperature sensors Tungsten Temperature Sensitivity tungsten trioxide Gas sensing operating temperature thermo-gravimetric analysis
Content Type	Text
Resource Type	Article
Subject	Electrical and Electronic Engineering

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