Modulation of band gap by normal strain in SiC-based heterostructures

The structure and electronic properties of Ge/SiC van der Waals (vdW) heterostructures under the influence of normal strain have been investigated by the first-principles method. Without a strain, the system shows a small band gap of 126 meV. By applying a normal strain, the band gap monotonically decreases from 126 to 0 meV. Our results reveal that the compressive strain has much influence on the band gap of the bilayer. The variations of band gap are owing to different states of Ge, Si, and C atoms in the conduction band and valence band. Moreover, electrons among Ge/SiC vdW heterostructures are likely to transfer from germanene to SiC monolayer due to the deeper potential of SiC monolayer. The predicted normal strain tunable band gap of the Ge/SiC vdW heterostructures is very promising for its potential use in nanodevices.