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Triple Gate Polycrystalline-Silicon-Based Ion-Sensitive Field-Effect Transistor for High-performance Aqueous Chemical Application
摘要： In this study, we developed a polycrystalline-silicon (poly-Si) thin-film transistor (TFT)-based, high-performance ion-sensitive field-effect transistor (ISFET) pH sensor that far surpasses the sensitivity of dual-gate pH sensors. A Triple gate structure on the same plane as the channel of the ISFET has been proposed to enhance the pH sensitivity. In a poly-Si TFT-based ISFET, a Triple gate is more advantageous than a bottom-gate for increasing capacitive coupling with the top-gate. As a result, the pH sensitivity by Triple gate (TG) mode detection using the Triple gate is much greater than single-gate (SG) mode detection using the top-gate, or dual-gate (DG) mode detection using the bottom-gate. The sensitivity of the TG mode greatly increased compared with the sensitivity of the conventional SG mode or DG mode. The measured pH sensitivity was 57.75 ± 0.77 mV/pH in the SG mode, 467.08 ± 9.92 mV/pH in the DG mode. In particular, the TG mode gives a maximum sensitivity of 1283.56 ± 45.54 mV/pH for a sensing membranes having a theoretical Nernstian pH response (59.15 mV/pH at 25 °C). Furthermore, we measured the hysteresis and drift characteristics, and found that the TG mode has improved non-ideal behavior compared to the SG and DG modes. Therefore, the poly-Si TFT-based TG ISFET pH sensor has the potential to become a promising biosensor application platform, with excellent sensitivity and stability.
关键词： ion-sensitive field effect transistor,Triple gate,capacitive coupling effect
更新于2025-09-23 15:22:29
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Improved pH Sensitivity and Reliability for Extended Gate Field-Effect Transistor Sensors Using High- <i>k</i> Sensing Membranes
摘要： In this study, we fabricated extended-gate (EG) ?eld-effect transistor (FET) pH sensors with dual-gate (DG) structures, using a range of dielectric sensing membranes (SiO2, Si3N4, HfO2 and Ta2O5) to vary their sensitivity. The fabricated EGFETs consisted of a silicon-on-insulator (SOI)-based metal-oxide semiconductor ?eld-effect transistor (MOSFET) transducer and an EG sensor. We ampli?ed the sensitivity of the device far beyond the Nernst limit (59 mV/pH), which is the theoretical maximum of conventional ion-selective FET (ISFET) sensing, by applying capacitive coupling. Among the evaluated dielectric sensing membranes, we obtained the highest sensitivity (478 mV/pH), low hysteresis (100.2 mV) and drift rate (24.6 mV/h) from the pH sensor with a Ta2O5 membrane. Hence, we expect DG FET con?gurations using Ta2O5 ?lms as EG sensing membranes to be useful for high performance biosensor applications, as they satisfy the requirements for sensitivity, stability and reliability.
关键词： Ion-Sensitive Field-Effect Transistor,Sensitivity,High-k Sensing Membrane,Dual-Gate Field-Effect Transistor,pH Sensor,Capacitive Coupling
更新于2025-09-09 09:28:46