Nonideal Factors of Ion-Sensitive Field-Effect Transistors with Lead Titanate Gate

Abstract

Sol–gel-derived lead titanate (PbTiO3) membranes have been successfully applied as H-ion-sensitive layers onto ion-sensitive field-effect transistors (ISFETs), yielding the quasi-Nernstian responses of 56–59 mV/pH. The effects of nonideal factors, such as stable response time, drift, hysteresis, lifetime and temperature, on the characteristics of the PbTiO3 gate ISFET have been investigated. Experimental results show a stable response time of 2–4 min, a drift of 0.5–1 mV/h and a hysteresis of 3–5 mV. Moreover, the PbTiO3 gate ISFET is long-lived, which has a lifetime of more than one year and a reduced pH sensitivity of about -10 µV/pH-day. The thermal effect on the PbTiO3 gate ISFET can mainly be attributed to the buffer solution and semiconductor because the PbTiO3-senstive membrane is unsusceptible to ambient temperature.