Novel floating-gate structure of In2O3 thin-film transistor-based gas sensor for improved gas sensing properties

Abstract

Metal oxide thin-film transistor (TFT)-based gas sensors are extensively studied due to their high sensitivity, fast response, easy manufacturing, and simple structure. However, research on utilizing the electrical properties of metal oxide TFT-based gas sensors to enhance gas sensing characteristics remains limited. In this study, we propose and fabricate a novel metal oxide TFT-based gas sensor with a lateral floating-gate (FG) structure and an embedded micro-heater, using only five photomasks. The sensor demonstrates efficient program and erase operations, which can be utilized to modulate the gas sensing characteristics. When the sensor operates in the program state, the response to oxidizing gas (NO2) increases, while the response to reducing gas (H2S) decreases. Conversely, when the sensor operates in the erase state, the opposite trend is observed. This approach can be utilized to improve the selectivity in reactions with oxidizing and reducing gases. Additionally, the embedded micro-heater allows independent control of the operating temperature of the sensor with low-power consumption. The sensor can be heated to 300℃ using the embedded micro-heater, consuming only 2.94mW of power.