Modeling of carbon nanotube ISFETs with high‐κ gate dielectrics for biosensing applications

Abstract

AbstractAn electrochemical model for two fabricated CNT‐ISFETs has been developed by considering all chemical and physical parameters of the device and then simulated in MATLAB environment. Model has been developed by studying on some aspects of carbon nanotube‐based ion sensitive field effect transistor (CNT‐ISFET) with two high‐κ dielectric materials (HfO2 and ZrO2) fabricated by chemical solution process at low temperature. DC experiments have been performed on pH of the solution to determine the dependence of surface potential, threshold voltage, and drain current. Sensitivities of the devices have also been determined experimentally and found to be 57.5 and 60 mV/pH compared with theoretical values of 56.6 and 58.6 mV/pH for HfO2 and ZrO2 CNT‐ISFETs, respectively in the pH range of 5 to 9. Time domain experiments have been performed to determine the memory effects of the devices. Experiments showed drift rate of 0.52 and 0.683 mV/h at pH 7 for HfO2 and ZrO2 as gate oxides, respectively. The hysteresis widths are found to be 5.88 and 5.26 mV in a pH loop of 7 → 9 → 7 → 5 → 7 for loop time of 60 minutes, respectively, for HfO2 and ZrO2 dielectrics. The simulated results of the developed model are compared with experimentally obtained data and found to be in good agreement.