Due to the atomic level thickness and novel properties, two-dimensional (2D) materials have received extensive attention on the research and application of future nanodevices. In this paper, the mechanical and electronic properties of $\alpha \text{−}{M}_2{X}_3$ ($M$ = Ga, In; $X$ = S, Se) monolayers are studied to explore their applications in 2D electronic devices. First-principles calculations based on density functional theory indicate that these four $\alpha \text{−}{M}_2{X}_3$ monolayers are all semiconductors and possess Young's modulus of less than 100 ${\mathrm{N}\mathrm{m}}^{-1}$ with a deformation range up to about 30%. In addition, the carrier mobility of the $\alpha \text{−}{M}_2{X}_3$ monolayer exceeds 600 ${\mathrm{cm}}^2{\mathrm{V}}^{-1}{\mathrm{s}}^{-1}$ and remains high under strain. In particular, because the band edge shifts under compressive strain, the electron mobility of the $\alpha \text{−}{\mathrm{Ga}}_2{\mathrm{S}}_3$ monolayer increases to about 1800 ${\mathrm{cm}}^2{\mathrm{V}}^{-1}{\mathrm{s}}^{-1}$ at $-3\%$ strain, which is approximately three times the value without strain. The excellent ductility and strain-promoted electronic properties make the 2D $\alpha \text{−}{M}_2{X}_3$ promising candidates for the application of flexible electronic devices.

• Received 13 January 2022
• Revised 13 June 2022
• Accepted 14 June 2022

DOI:https://doi.org/10.1103/PhysRevB.105.235303