High-Performance Dual-Gate Carbon Nanotube Ion-Sensitive Field Effect Transistor With High- $\kappa$ Top Gate and Low- $\kappa$ Bottom Gate Dielectrics

We have reported the fabrication and characterization of dual-gate (high-κ as top gate and low-κ as bottom gate dielectrics) carbon nanotube (CNT) ion-sensitive field effect transistor (DG-CNTISFET) for detection of pH of electrolyte. To improve the sensing performance beyond the Nernstian sensitivity limit of 59 mV/pH at room temperature (25°C), HfO
₂
(κ -.25) has been used as a top gate dielectric and ZnO (κ -.1.5) as a bottom gate dielectric. The device has been fabricated by chemical solution process (using AUTOLAB Potentiostat/Galvanostat PGSTAT128N system) and characterized in electrolyte solutions of range 5-9 pH. In this range of pH, the device has shown a good linearity and an improved sensitivity of 943 mV/pH at room temperature. The device showed the drift rate of 13.5 mV/pH at pH 7 and the hysteresis width of 15.8 mV in a pH loop of 7 → 9 → 7 → 5 → 7. These suppressed non-ideal effects of the device along with the high sensitivity are suitable for nanobiosensing applications.