3D-strain-induced multiple semiconductor–metallic phase transition in monolayer SrTiO3

Abstract

The recent discovery of monolayer perovskite has attracted much attention due to its abundant physical properties and extreme flexible properties. However, multiple strain effects on its physical properties are not clear. Herein, by means of first-principles calculations, we show that under 3D-multiple strains, the monolayer SrTiO3 (STO) can be tuned from the semiconductor into metallic phases via the in-plane strain engineering. The bandgap of the monolayer STO increases with increasing positive biaxial strain and reduces to zero when a negative biaxial strain is applied. In addition, we found that the metallic phase of the monolayer STO under the in-plane biaxial strain will drop back into the semiconductor phase when an out-of-plane compressive strain is added. By analyzing the electronic band structure, density of states, and orbital-projected band structures, we found that the p-orbitals of Sr and O atoms as well as the d-orbitals of Sr atoms make significant effects on the multiple semiconductor–metallic phase transition. In summary, the abundant semiconductor–metallic phase transition of the monolayer STO under 3D-strain conditions opens up an opportunity for its application in modulating the electronic properties of 2D materials.