Tunable Electronic Properties and Giant Spontaneous Polarization in Graphene/Monolayer GeS van der Waals Heterostructure

Van der Waals (vdW) heterostructures consisting of two-dimensional-layered nanomaterials have attracted great attention due to their promising applications in novel electronic and optoelectronic devices. Using density functional theory (DFT) with the vdW correlations (DFT-D), the electronic properties and spontaneous polarization of graphene/monolayer GeS (G/MGeS) heterostructure have been investigated. It is found that the properties of both graphene and GeS are preserved in the vdW heterostructure, and the electronic structure of the heterostructure is advantageous for improving photocatalytic efficiency. Moreover, it is also found that the position of the band structure of GeS with respect to that of graphene can be tuned by altering the interlayer spacing, which further led to the control of the Schottky barrier height of the vdW heterostructures. Additionally, the vdW heterostructure shows increased spontaneous polarization (186.6 mu Ccm(-2)) as well as increased energy barrier heights, which indicate the enhanced ferroelectricity in the heterostructure. Further investigation demonstrates that the compressive strain can have a significant impact on both the spontaneous polarization and the energy barrier height of the vdW heterostructure.