Ultralow-Power DST-TFET pH Sensor Exceeding the Nernst Limit with Influence of Temperature on Sensitivity

In this paper, a dual-source T-channel TFET (DST-TFET)-based pH sensor demonstrating the pH change in the electrolyte has been studied. The proposed device exceeds the Nernst limit of 59 mV/pH by ∼5 folds. The simulation is performed on an ATLAS TCAD tool (SILVACO) and pH is determined by calculating the interface charge density (Δσ) using appropriate physics models. The voltage sensitivities, using various oxides (SiO₂, HfO₂, Al₂O₃) with a maximum achieved sensitivity (S_V) of 297.66 mV/pH ∼5× Nernst limit, have been calculated. Moreover, this high value of S_V is achieved at an ultralow operating voltage of 0.1 V. The results have been validated by proper calibration of models with the experimental data. It is evident from the results that DST-TFET performs well at ultralow power compared to several previously reported devices. Furthermore, the temperature study has been implemented in the proposed sensor to investigate the I_DS-V_GS characteristics and sensing performance of the device. The pH sensitivity and voltage sensitivity decreased with increase in temperature. The proposed pH sensor with such high sensitivity is an exclusive choice for pH-sensing applications.