We report an amorphous indium gallium zinc oxide (IGZO)-based toxic gas detection system. The microsystem contains an IGZO thin-film transistor (TFT) as a sensing element and exhibits remarkable selectivity and sensitivity to low concentrations of nitrogen dioxide (NO2). In contrast to existing metal oxide-based gas sensors, which are active either at high temperature or with light activation, the developed IGZO TFT sensor is operable at room temperature and requires only visible light activation to revive the sensor after exposure to NO2. Furthermore, we demonstrate air-stable sensors with an experimental limit of detection of 100 ppb. This is the first report on metal oxide TFT gas sensors without heating or continuous light activation. Unlike most existing gas sensing systems that take care of identifying the analytes alone, the developed IGZO microsystem not only quantifies NO2 gas concentration but also yields a 5-bit digital output. The compact microsystem, incorporating readout and analog-to-digital conversion modules developed using only two TFTs, paves the way for inexpensive toxic gas monitoring systems.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: We are thankful to Prof. TH Hou and Yi-Hsui Lai from National Chiao-Tung University, Taiwan (NCTU, Taiwan), for valuable discussions. We are also thankful to thin-film (TF) lab, Nanofabrication (NCL), and Imaging and Characterization (IAC) core labs’ staff of KAUST for their help throughout.