Highly sensitive and selective room-temperature NO 2 gas-sensing characteristics of SnO X -based p-type thin-film transistor

Abstract

The high-performance p-type metal-oxide-semiconductor (MOS)-based gas sensor is an important subject of research in the field of gas-sensing technology. In this work, we demonstrated a p-type MOS-based thin-film transistor (TFT) nitrogen dioxide (NO 2 ) gas sensor that used tin oxide (SnO X ) for both the channel and sensing layers. The crystalline status, surface morphology, and atomic-bonding configuration of the thin-film were examined using X-ray diffraction, field emission-scanning electron microscopy, and X-ray photoelectron spectroscopy. The results indicated that the deposited thin-film was mainly composed of polycrystalline SnO with a tetragonal structure. The fabricated p-type SnO X TFT showed a maximum response value of 19.4-10 ppm NO 2 at room temperature (RT, 25 °C) when operated in the subthreshold region, which was significantly higher than that of 2.8–10 ppm NO 2 obtained from a p-type SnO X thin-film chemiresistor at RT. In addition, the SnO X TFT gas sensor showed significantly higher sensitivity to NO 2 gas than to other target gases such as NH 3 , H 2 S, CO 2 , and CO at RT. To the best of our knowledge, this is the first study to a p-type MOS-based field-effect transistor-type gas sensor. Our experimental results demonstrate that the p-type SnO X TFT is a promising gas sensor that can operate at RT with high sensitivity and selectivity to NO 2 gas. © 2019 Elsevier B.V.