This contribution deals with Carbon Nanotubes Field Effect transistors (CNTFETs) based gas sensors fabricated using a
new dynamic spray based technique for SWCNTs deposition. This technique is compatible with large surfaces, flexible
substrates and allows to fabricate high performances transistors exploiting the percolation effect of the SWCNTs
networks achieved with extremely reproducible characteristics. Recently, we have been able to achieve extremely
selective measurement of NO2 , NH3 and DMMP using four CNTFETS fabricated using different metals as electrodes
(Pt, Au, Ti, Pd), exploiting the specific interaction between gas and metal/SWCNT junction. In this way we have identify
a sort of electronic fingerprinting of the gas. The time response is evaluated at less than 30sec and the sensitivity can
reach 20ppb for NO2, 100ppb for NH3 and 1ppm for DMMP (Di-Methyl-Methyl-Phosphonate).
Our study deals with the utilization of carbon nanotubes networks based transistors with different metal
electrodes for highly selective gas sensing. Indeed, carbon nanotubes networks can be used as semi
conducting materials to achieve good performances transistors. These devices are extremely sensitive to the
change of the Schottky barrier heights between Single Wall Carbon Nanotubes (SWCNTs) and drain/source
metal electrodes: the gas adsorption creates an interfacial dipole that modifies the metal work function and so
the bending and the height of the Schottky barrier at the contacts. Moreover each gas interacts specifically
with each metal identifying a sort of electronic fingerprinting. Using airbrush technique for deposition, we
have been able to achieve uniform random networks of carbon nanotubes suitable for large area applications
and mass production such as fabrication of CNT based gas sensors. These networks enable us to achieve
transistors with on/off ratio of more than 5 orders of magnitude. To reach these characteristics, the density of
the CNT network has been adjusted in order to reach the percolation threshold only for semi-conducting
nanotubes. These optimized devices have allowed us to tune the sensitivity (improving it) of our sensors for
highly selective detection of DiMethyl-Methyl-Phosphonate (DMMP, a sarin stimulant), and even volatile
drug precursors using Pd, Au and Mo electrodes.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.