Sensor applications of InGaZnO thin-film transistors

This article reviews and discusses sensor applications of bottom-gate type InGaZnO thin-film transistors (TFTs). First, we discuss specific features of InGaZnO TFTs that differentiate them from Si-based TFTs, such as the significant capacitive coupling between the bottom-gate and top-gate electric fields and material properties such as carrier generation mechanism. Although flat-panel displays driven by InGaZnO TFTs have been developed, these features have not necessarily been utilized. Based on these features, next, we review and discuss possible chemical-sensor concepts of InGaZnO TFTs, like gas sensors, pH sensors, and biochemical sensors. We also cover possible physical-sensor concepts like photo sensors, temperature sensors, and electrostatic potential sensors. Regarding these sensor concepts, the passivation layer in the InGaZnO TFTs or the InGaZnO layer itself works as the sensitive membrane that responds to particular substances. These sensor concepts can provide a way to incorporate InGaZnO TFTs into a wide variety of sensor applications.