Improvement of NO2 gas-sensing properties in InGaZnO thin-film transistors by a pre-biasing measurement method

Abstract

In this work, we investigated the effectiveness of a pre-biasing measurement technique for improving the gas-sensing performance of a metal oxide semiconductor (MOS)-based thin-film transistor (TFT)-type gas sensor for the first time. Various pre-biases voltages were applied to an indium-gallium-zinc oxide (IGZO) TFT gas sensor, and the resulting effects on NO2 detection performances were examined at various NO2 concentrations and temperatures. Our results showed that the NO2 sensing performance of the IGZO TFT sensor could be significantly improved by application of a positive pre-bias voltage to the gate electrode of the IGZO TFT. The impact of pre-bias voltage application was more significant when the pulse amplitude and width were increased, especially at temperatures below 90 degrees C. Enhancement of IGZO TFT NO2 sensor performance was attributed to an electric-field-induced chemisorption of NO2 on the active back channel of the IGZO TFTs during pre-bias voltage application. Our results demonstrated that the pre-biasing measurement technique is a simple and effective biasing scheme that can enhance the gas-sensing performance of three-terminal TFT-type gas sensors that employ MOS for both the channel and sensing layers.