Abstract
Abstract. In this work we report on the development of back-gated carbon nanotube-field effect transistors (CNT-FETs), with CNT layers playing the role of the channel, and on their electrical characterisation for sensing applications. The CNTs have been deposited by electrophoresis on an interdigitated electrode region created on a SiO2/Si substrate. Different kinds of CNTs have been used (MWCNTs by arc discharge in liquid nitrogen and MWCNTs by chemical vapour deposition, CVD) and the electrical characterisation of the devices was performed in a NH3- and NO2-controlled environment. Preliminary data have shown an increase in the channel resistance under NH3 exposure, whereas a decrease is observed after exposure to NO2, and the sensitivity to each gas depends on the kind of CNTs used for the device. Furthermore, the defect formation by Si ion implantation on CNTs was investigated by high-resolution transmission electron microscopy (TEM) and Raman analysis. The behaviour observed for the different devices can be explained in terms of the interaction between structural or chemical defects in CNTs and the gas molecules.
Highlights
Since their discovery, carbon nanotubes (CNTs) have aroused great interest due to their exceptional properties related to their one-dimensional character (Deretzis et al, 2006) like a high current-carrying capacity, high thermal conductivity and reduced charge carrier scattering
Two types of CNTs were used to investigate the sensing properties of the devices produced: commercial MWCNTs synthesised by the Sigma Aldrich CoMoCAT catalytic CVD process, hereafter called MWCNTs-CVD, and MWCNTs synthesised by arc discharge in liquid nitrogen (LN2) and oxidised in H2O2 for 2 h in an ultrasonic bath (Bagiante et al, 2010; Scalese et al, 2010), hereafter called MWCNTs-LN2
The device with MWCNTs-LN2 shows a better sensitivity to NH3 compared to the device with MWCNTs-CVD (Fig. 3a), while the device with MWCNTs-CVD shows a better sensitivity to NO2 compared to the other one (Fig. 3b)
Summary
Carbon nanotubes (CNTs) have aroused great interest due to their exceptional properties related to their one-dimensional character (Deretzis et al, 2006) like a high current-carrying capacity, high thermal conductivity and reduced charge carrier scattering. The use of both individual nanotubes and CNT networks has been explored, depending on the specific applications (Zhou et al, 2002). Back-gated carbon nanotube-field effect transistors (CNT-FETs) have been produced where a CNT network forms the channel of the FET, and the role of defects in the sensing properties, already present or induced by ion implantation on the CNT walls, has been investigated
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