Two-dimensional (2D) transition-metal dichalcogenides have attracted significant attention as gas-sensing materials owing to their superior responsivity at room temperature and their possible application as flexible electronic devices. Especially, reliable responsivity and selectivity for various environmentally harmful gases are the main requirements for the future chemiresistive-type gas sensor applications. In this study, we demonstrate improved sensitivity of a 2D MoS2-based gas sensor by controlling the Schottky barrier height. Chemical vapor deposition process was performed at low temperature to obtain layer-controlled 2D MoS2, and the NO2 gas responsivity was confirmed by the fabricated gas sensor. Then, the number of MoS2 layers was fixed and the types of electrode materials were varied for controlling the Schottky barrier height. As the Schottky barrier height increased, the NO2 responsivity increased, and it was found to be effective for CO and CO2 gases, which had little reactivity in 2D MoS2-based gas sensors.
Keywords: Chemical vapor deposition; Gas sensor; Molybdenum disulfide; NO2; Schottky barrier; Schottky contact; Transition-metal dichalcogenide.