The gas sensing properties of single-walled carbon nanotubes deposited on an aminosilane monolayer

This paper presents our study on the effects of an aminosilane monolayer on the gas sensing properties of single-walled carbon nanotubes (SWCNTs). A gas sensor for nitrogen dioxide (NO2) detection was fabricated by conventional photolithography process on an oxidized silicon wafer functionalized with 3-aminopropyltriethoxysilane (APTES). Such a CNT-based gas sensor was found to result in high sensitivity and fast response time compared with the sensor fabricated on a non-silanised surface. The amine groups in the APTES monolayer, electron donating in nature, played a role of charge transfer to the semiconducting SWCNTs, and hence the amount of electrons transferred from SWCNTs to NO2 molecules increased. Our results suggest that the APTES intended originally for selective placement of individual SWCNTs could be used to enhance the gas sensing properties of the SWCNTs.