A highly sensitive chemical gas detecting transistor based on highly crystalline CVD-grown MoSe2 films

Layered semiconductors with atomic thicknesses are becoming increasingly important as active elements in high-performance electronic devices owing to their high carrier mobilities, large surface-to-volume ratios, and rapid electrical responses to their surrounding environments. Here, we report the first implementation of a highly sensitive chemical-vapor-deposition-grown multilayer MoSe 2 field-effect transistor (FET) in a NO 2 gas sensor. This sensor exhibited ultra-high sensitivity ( S = ca. 1,907 for NO 2 at 300 ppm), real-time response, and rapid on–off switching. The high sensitivity of our MoSe 2 gas sensor is attributed to changes in the gap states near the valence band induced by the NO 2 gas absorbed in the MoSe 2 , which leads to a significant increase in hole current in the off-state regime. Device modeling and quantum transport simulations revealed that the variation of gap states with NO 2 concentration is the key mechanism in a MoSe 2 FET-based NO 2 gas sensor. This comprehensive study, which addresses material growth, device fabrication, characterization, and device simulations, not only indicates the utility of MoSe 2 FETs for high-performance chemical sensors, but also establishes a fundamental understanding of how surface chemistry influences carrier transport in layered semiconductor devices.