Controllable Oxygen-Incorporated 2D-SnSe₂ Layered Thin Film by Plasma-Assisted Selenization Process with Enhanced NO₂ Gas Sensitivity and Improved Humidity Stability

Herein, oxygen-incorporated 2D-SnSe₂ layered films are successfully fabricated by a plasma-assisted selenization process. The oxygen concentrations inside the 2D-SnSe₂ layered film are controllable by controlling the proportion of hydrogen in the mixed gas of nitrogen and hydrogen during the plasma-assisted selenization reaction. Oxygen atoms mainly exist in the form of the incorporated oxygen in the 2D-SnSe₂ layered film with an exceedingly small grain size of SnO₂, which significantly increases the total interface area of the SnO₂/SnSe₂. Significant enhancement of the gas response to NO₂ (709% under 100 ppb NO₂) is reached when the proportion of hydrogen during the plasma-assisted selenization process is 25%, thus showing excellent sensitivity and selectivity. Moreover, the sensor also demonstrated excellent stability under an increase in relative humidity. It is verified that the response will not significantly decrease when the relative humidity is below 90%. The obtained results demonstrate that oxygen-incorporated 2D-SnSe₂ layered film with excellent commercial potential, is a highly suitable candidate for next-generation gas sensors.