a-InGaZnO Thin-film Transistor as an Oxygen Gas Sensor with In-Situ Electrical Characterization

Wide band gap metal oxide semiconductors have been explored for a plethora of applications in recent years [1]. Thin film transistors (TFTs) especially have found extensive utility in environmental sensors and flexible electronics for modern devices. Amorphous Indium Gallium Zinc Oxide (a-IGZO) is a wide band gap metal oxide semiconductor with ideal properties for next generation sensors. It's transparent thin film coupled with wide band gap and high field effect mobility provides an ideal platform for such sensors. It's stability and high mobility gives it a major advantage over the organic TFTs that have been traditionally used for such sensing applications. Oxygen sensors has seen large demand recently owing to the modernization of agricultural methods and in biomedical applications where it is of critical importance. In the present work an a-IGZO TFT is fabricated and demonstrated for oxygen sensing with in-situ electrical characterization. a-IGZO thin films are prepared by simple, low-cost solution processing. The a-IGZO TFT is used to sense oxygen (O2) gas and ppm level detection is achieved. The effect of change in electrical characteristics of IGZO TFTs with oxygen adsorption is utilized to achieve high sensitivity [2]. The saturation drain current $(\mathrm{I}_{\text{Dsat}})$ increment of 20 uA/ppm and Vth shift of 100mV/ppm in presence of oxygen is observed.