Sensing of CO and NO on Cu-Doped MoS₂Monolayer-Based Single Electron Transistor: A First Principles Study

Abstract

Owing to the large surface area, 2-D materials are being used for sensing gas molecules, which are important for environmental protection and human health. Using first principle calculations, adsorption of CO and NO gas molecules on Cu-substituted monolayer MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> is studied in terms of energy, charge transfer, and density of states. Further, the behavior of CO and NO on Cu-substituted monolayer MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -based single electron transistor (SET) is explored. Strong interaction between Cu metal and MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> sheet suggests the stability of the Cu-doped MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> system at ambient conditions. It is further found that on doping Cu into MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> sheet, the adsorption strength of CO and NO molecules got enhanced as compared with the pristine MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> sheet and, hence, possesses better sensing capability. The sensing response of the Cu-doped MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> sheet in the SET environment toward these molecules is studied from the calculated charge stability diagram that serves as a unique fingerprint of each adsorbed molecule. The charging energy is reduced when Cu impurity is added to MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> for CO/NO adsorption, which makes such system more suitable in low-powered SET devices. The results show that SET based on Cu-doped MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> can essentially detect hazardous molecules and is proved to have potential application in gas sensors.