Fast-response/recovery In2O3 thin-film transistor-type NO2 gas sensor with floating-gate at low temperature

Metal-oxide (MOX)-based gas sensors have various advantages such as high response, fast sensing dynamics, and ease of fabrication. However, MOX-based gas sensors require high temperature for gas response and recovery, which requires large power consumption. Therefore, low-temperature operation in the MOX-based gas sensor is an important feature in terms of power-efficiency. In this work, In2O3 thin film transistor (TFT)-type NO2 gas sensor with floating-gate (FG) is fabricated, which is capable of fast response and recovery at low temperature (75 ℃). The sensor is designed to enable modulating its gas sensing properties by engineering the quantity of charge stored in FG. Specifically, the response characteristics of the sensor are significantly improved at 75 ℃ by operating the sensor in erase state. Furthermore, to quickly recover the sensor, pulsed bias recovery method is proposed. By applying pulsed negative bias to the gate electrode, NO2- molecules adsorbed to In2O3 sensing layer are desorbed quickly. Therefore, the sensor is recovered rapidly within a second even at 75 ℃. The proposed methods enhance the gas sensing properties including the response and recovery at low temperature, significantly improving the power-efficiency in MOX-based TFT-type gas sensor.