Semiconducting single-walled carbon nanotube network-based double-gate thin-film transistors for high-performance aqueous chemical sensor applications

In this study, we fabricated a highly sensitive separative extended gate chemically modified field effect transistor (SEG-ChemFET) sensor using a semiconducting single-walled carbon nanotube (scSWCNT) network. To improve the stability and sensitivity of the scSWNT channel layer, we fabricated a double-gate structure FET transducer with a passivated channel using top- and bottom-gate insulators and applied a separate sensing membrane. The scSWCNT network channel was formed by solution process. In order to increase the sensitivity, a low-k spin-on-glass (SOG) film and a stacked Ta2O5/SiO2 film were formed as top-gate and engineered bottom-gate insulators, respectively, which improved the coupling ratio. As a result, the fabricated scSWCNT ChemFET sensor exhibited sensitivity of 365.65 mV/pH sensitivity, which is much higher than the Nernst limit (59.5 mV/pH), a linearity of 99.88%, and a drift rate of 72.44 mV/h. Thus, we expect this research to have important applications for high-sensitivity biosensors.