Van der Waals heterostructure gas sensors based on narrow-wide bandgap semiconductors for superior sensitivity

Achieving high sensitivity in gas sensors is crucial for the precise detection of toxic agents. However, this can be challenging as it requires gas sensors to possess both a high response signal and low electrical noise simultaneously, which seems controversial as it necessitates adopting semiconductors with different bandgaps. Herein, we demonstrate the superior sensitivity of 2D molybdenum disulfide (MoS2)/tellurium (Te) van der Waals heterostructure (vdWH) gas sensors fabricated by combining narrow-bandgap (Te) and wide-bandgap (MoS2) semiconductors. The as-fabricated MoS2/Te vdWH gas sensors exhibit excellent sensitivity that is unavailable for sensors based on its individual counterparts. The response toward 50 ppm NH3 is improved by two and six times compared to the individual MoS2 and Te gas sensors, respectively. In addition, a high signal-to-noise ratio of similar to 350 and an ultralow limit of detection of similar to 2 ppb are achieved. These results outperform most previously reported gas sensors due to the efficient modulation of the barrier height of the MoS2/Te p-n junction as well as the synergistic effect benefiting from the low electric noise of the narrow-bandgap Te and high response signal of the wide-bandgap MoS2. Our work provides an insight into utilizing vdWHs based on narrow-wide bandgap semiconductors for developing highly sensitive gas sensors.