A two-dimensional
(2D) Ga2O3 monolayer with
an asymmetric quintuple-layer configuration was reported as a novel
2D material with excellent stability and strain tunability. This unusual
asymmetrical structure opens up new possibilities for improving the
selectivity and sensitivity of gas sensors by using selected surface
orientations. In this study, the surface adsorptions of nine molecular
gases, namely, O2, CO2, CO, SO2,
NO2, H2S, NO, NH3, and H2O, on the 2D Ga2O3 monolayer are systematically
investigated through first-principles calculations. The intrinsic
dipole of the system leads to different adsorption energies and changes
in the electronic structures between the top- and bottom-surface adsorptions.
Analyses of electronic structures and charge transport calculations
indicate a potential application of the 2D Ga2O3 monolayer as a room-temperature NO gas-sensing device with high
sensitivity and tunable adsorption energy using plenary strain-induced
lattice distortion.