Review of Thin Film Transistor Gas Sensors: Comparison with Resistive and Capacitive Sensors

Abstract

The present review concerns thin film field effect transistor (TFT)-based gas sensors with special emphasis on material synthesis, electrical characterizations and sensing properties. A comparative analysis of TFT sensors with that of resistive and capacitive sensors is carried out. Comparison reveals that resistive and capacitive sensors have higher sensitivity, whereas TFT sensors offer improved selectivity and higher reliability. This is attributed to gate voltage-induced carrier transport through the sensing channel that reduces the need for higher operating temperature unlike in the case of resistive and capacitive devices. The gas-sensing mechanism is co-related considering adsorption-desorption isotherms and work function modulation at the gas-solid interface. Type of electrode and density of surface states play a major role for sensitivity and reliability enhancement. Factors influencing stability, repeatability and selectivity improvement are also discussed.