Sensitivity Determination of CNT-Based ISFETs for Different High-κ Dielectric Materials

Two carbon nanotube (CNT)-based ion sensitive field effect transistors (CNTISFETs): one using HfO2 and the other ZrO2 as dielectric materials have been fabricated by electrochemical deposition (ECD) technique. After fabrication, these two devices have been electrically characterized, and sensitivities have been determined experimentally and found to be 57.5 mV/pH and 60 mV/pH for HfO2 and ZrO2, respectively, in the pH range 5-9 at room temperature. The pH sensitivities of HfO2 and ZrO2 have also been determined theoretically by using van Hal's model and simulated in a MATLAB environment. The theoretical sensitivity is determined in terms of intrinsic buffer capacity and differential capacitance. The theoretical sensitivities of HfO2 and ZrO2 dielectrics are found to be 57.1 mV/pH and 58.61 mV/pH, respectively, in the pH range 5-9. Moreover, these CNTISFETs demonstrate lower drift rate and smaller hysteresis width compared to previously fabricated devices available in the literature.