Two-dimensional SnS2 for detecting gases causing “Sick Building Syndrome”

Two-dimensional tin disulfide (SnS2) film formed by chemical vapor deposition (CVD) has been used as a sensing material for formaldehyde (HCHO), a notorious gas causing “Sick Building Syndrome”. We have found that a sensor based on SnS2-chanel field-effect-transistor (FET) exhibits a clear response to HCHO with concentrations as low as 1 ppb in N2. Moreover, sensing tests of the sensor in dry air also showed a higher sensitivity to HCHO than previously-reported sensors using metal oxide nanoparticles [1] or rGO/TiO
₂
composite [2]. The sensor further exhibited a good selectivity of HCHO among other organic species. Simulations suggest that possible sulfur vacancies in SnS
₂
play a crucial role in detecting HCHO. In fact, it has been shown that oxygen atoms that are unexpectedly detached from HCHO molecules can fill the vacancies, lowering the Fermi level of SnS2. Furthermore, considering future mass-production of sensors, we have succeeded in wafer-scale synthesis of SnS2 film by means of magnetron sputtering and post annealing processes.