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 NO 2 detection performances were examined at various NO 2 concentrations and temperatures. Our results showed that the NO 2 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 °C. Enhancement of IGZO TFT NO 2 sensor performance was attributed to an electric-field-induced chemisorption of NO 2 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.

Fully Integrated Indium Gallium Zinc Oxide NO2 Gas Detector

“…Transfer characteristics and output characteristics were measured by keeping V DS = 1 V and V GS = 15 V, respectively. It was observed that with the increase in NO 2 concentration, there was a positive shift in the V th and a decrease in the drain current ( I D ) of the TFT; this is consistent with the reported IGZO TFT-based sensors, , as shown in Figure a,b. There was a substantial change in the V th and I D of IGZO TFTs proportional to the concentration of NO 2 .…”

“…Because the channel of the TFT was oxidized after NO 2 exposure, these devices could not be recovered even after a prolonged N 2 purge (Figure a) owing to the strong bonding of gas molecules with the active area. Similarly, Kim et al observed the adsorption of NO 2 with an IGZO active layer and could not recover the device after exposure at room temperature. , The semiconducting channel properties could be revived only after the application of some external energy. Hence, we explored the revival of TFT sensors using light activation, as IGZO is reported to have excellent photoelectric characteristics .…”

“…31 However, non-passivated IGZO TFT's electrical characteristics are sensitive to ambient oxygen. 32 There are some reports on IGZO as an active layer to detect NO2, [33][34][35][36] but these sensors require either UV activation 35 or high temperature for sensing and recovery, [33][34]36 which are typical requirements of SMO gas sensors. In the present work, we propose a gas sensor using IGZO as the active layer for sensing NO2 at room temperature without continuous light activation.…”

Conduction Band Edge Energy Profile Probed by Hall Offset Voltage in InGaZnO Thin Films

“…Oxide semiconductors are used in various applications, including flat-panel displays [ 1 , 2 ], optical sensors [ 3 , 4 ], and solar cells [ 5 , 6 ], owing to their excellent electrical and optical properties. Among them, the amorphous-InGaZnO (a-IGZO) thin-film transistors (TFTs) have attracted considerable attention for applications in flat-panel displays thanks to their high electrical performances [ 7 , 8 , 9 , 10 , 11 , 12 ] and manufacturability over a large area [ 13 ].…”

Micro/nanostructured gas sensors: the physics behind the nanostructure growth, sensing and selectivity mechanisms

“…It was observed that, sensing performance improved when the temperature increases to 90°C possibly attributed to the effect of electric-field-induced chemisorptions of NO 2 at the channel of the IGZO TFTs. 65 Most of the TFT based sensor faces the problem of baseline recovery (return of base line resistance before gas exposure). Recovery rate of the TFT based sensor can be improved by irradiation UV light at the sensing channel.…”