Two-dimensional MgX2Se4 (X=Al, Ga) Monolayer with Tunable Electronic Properties for Optoelectronic and Photocatalytic Applications
Two new two-dimensional (2D) layered materials, namely, MgX2Se4 (X=Al, Ga) monolayers, are predicted to exhibit novel electronic properties. Ab initio electronic structure calculations show that both MgAl2Se4 and MgGa2Se4 monolayers are direct-gap semiconductor with bandgap of 3.14 eV and 2.34 eV, respectively. The bandgap of both 2D materials is very sensitive to the in-plane biaxial strain, while the strain induced bandgap changes allow the tuning of optical absorption from violet to green-light region. Also importantly, the in-plane electron mobility of both 2D materials is predicted to be as high as ~0.7-1.0×103 cm2V-1s-1, notably higher than that of the MoS2 sheet (~200 cm2V-1s-1), while are comparable to that of the black phosphorene (~1000 cm2V-1s-1), suggesting their potential application in n-type field-effect transistors. Moreover, suitable bandgap and band-edge alignment render the monolayer MgX2Se4 potential photocatalysts for water splitting. Lastly, we show that MgX2Se4 possess a lower layer cleavage energy than that of the graphite, indicating easy exfoliation of MgX2Se4 layers from their bulk.
- This article is part of the themed collection: 2019 Nanoscale HOT Article Collection