Adsorption and Gas Sensing Properties of GaAs Monolayer: A DFT Study

The Detection of hazardous gases is crucial for healthcare and industrial applications. GaAs monolayer can be a promising material for the selective detection of gases including $\mathrm{NH}_{3}, \mathrm{CO}$, and SO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>. This work investigates the gas adsorption properties of GaAs monolayer using the density functional theory. We determined the adsorption energy, distance, charge transfer, band structure, density of states, sensitivity, and recovery time for $\mathrm{NH}_{3}, \mathrm{CO}$, and SO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> molecules on GaAs monolayer. The results show that the adsorption properties of SO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> on GaAs monolayer is superior to NH<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> and CO molecules. In particular, the GaAs monolayer exhibited a high sensitivity of $5.073 \times 10^{6}$ and faster recovery toward SO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>, significantly superior to NH<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> and CO. The SO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> tends to be physisorbed on the GaAs monolayer, whereas CO and NH<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> prefer chemisorption. These different adsorption behaviors notably affect the band structures, charge transfer, and density of states. Thus, the obtained adsorption and gas sensing properties would be potential for developing GaAs-based sensing devices.