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Role of catalysts and their nanoscale dispersal on the response characteristics of SnO2 thin film H2S gas sensor

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Author(s): Arijit Chowdhuri | Monika Tomar | K. Sreenivas | Vinay Gupta

Journal: Philosophic Nature
ISSN 0974-4215

Volume: 1;
Issue: 2;
Start page: 195;
Date: 2009;
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Keywords: RF Sputtering | gas sensors | spillover mechanism

ABSTRACT
High quality SnO2 thin films with porous microstructure have been prepared using rf sputtering technique underreactive ambient (Ar + O2), and integrated with various metal and metal oxide catalysts for trace level (20 ppm)detection of H2S gas. Thin film sensors with novel hetero-structure (i) metal-layer (10nm)/SnO2-film (90 nm), and (ii)metal-cluster (10nm thin, 500μm dia.)/SnO2-film (90 nm) have been fabricated. Role of various metal (Ag, Zn, Pb, Pt,Pd, Cu, Ni) and metal oxide (NiO, CuO, Ag2O) catalysts for enhanced H2S gas sensing response characteristics arestudied systematically. Dispersal of catalysts in nanoscale (10 nm thin) range on the surface of sensing layer (SnO2) as(i) continuous overlayer and (ii) dotted clusters (dia. 500μm) have been investigated in light of the work-function andmodulation of barrier height at the interface of sensing layer and catalyst. The metal-oxide-cluster/SnO2-film sensorstructure is found to exhibit enhanced H2S gas sensing response (103 to 104), at relatively lower temperature (140 -150 C) for 20 ppm H2S gas. The enhanced sensing response characteristics are attributed to co-existence of catalyticcontrol mechanisms a) Spillover phenomena and b) Fermi-level interaction in the novel sensor hetero-structure.
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Tango Jona
Tangokurs Rapperswil-Jona