Ultra-low detection limit chemoresistive NO₂ gas sensor using single transferred MoS₂ flake: an advanced...

In this work, a method of fabricating a NO₂ nano-sensor working at room temperature with a low detectable concentration limit is proposed. A 2D-MoS₂ flake is isolated by transferring a single MoS₂ flake to SiO₂/Si substrate, followed by applying an advanced e-beam lithography (EBL) to form a metal contact with Au/Cr electrodes. The resulting chemoresistive nano-sensor using a single MoS₂ flake was applied to detect a very low concentration of NO₂ at the part-per-billion (ppb) level. This result is obtained due to the ability to create microscopic nano-sized MoS₂ gaps using e-beam lithography (300 nm-400 nm). Experimental results also show that the sensor can capture changes in concentration and send the information out extremely quickly. The response and recovery time of the sensor also reached the lowest point of 50 and 75 ms, outperforming other sensors with a similar concentration working range.