Temperature effects on the characteristics of hydrogen ion-sensitive field-effect transistors with sol–gel-derived lead titanate gates

The temperature effects on the characteristics of PbTiO3 gate ion-sensitive field-effect transistors (ISFETs) operated in the nonsaturation and saturation regions are investigated. The origin of this effect is explained by the ISFET model theory, operating in 5– 65 °C range. According to the experimental results, as operated in the nonsaturation region, the pH response increases monotonically as the temperature increases with a temperature coefficient of about 0.106 mV pH^-1 °C^-1. However, the linearity drops abruptly above 55 °C. The isothermal point, affected by both the electron mobility and threshold voltage, can be obtained at about IDS=40 (mu)A. Conversely, as operated in the saturation region, the drain-source current is dominated mainly by the electron mobility. The pH response decreases monotonically with an increase in temperature with a temperature coefficient of about -0.071 (mu)A pH^-1 °C^-1. The linearity also becomes worse at higher temperature.