Anisotropic strain effect on structural and electronic properties in WSe2/ZnO mixed-dimensional heterostructure

Abstract Mixed-heterostructures have received much attention due to their broader application in functional devices. Here, we investigate the strain effect on structural and electronic properties of 2D WSe2/1D ZnO nanoribbon (WSe2/ZnO-NR) mixed-dimensional heterostructure including the armchair ZnO nanoribbon (a-ZnO-NR) and zigzag ZnO nanoribbon (z-ZnO-NR) on WSe2 layer by using the first principles calculation. The results show that the binding strength of WSe2/ZnO-NR is enhanced. Remarkably, the WSe2/ZnO-NR presents anisotropic electronic properties under strain effect. Firstly, whether the WSe2/a-ZnO-NR is passivated by hydrogens or not, they always show type-I direct band gap alignment. After the strain applied, the band structures are transformed into type-II band alignment, promoting the separation of photogenerated electron-hole pairs. For WSe2/z-ZnO-NR, it exhibits type-II band alignment. The strain engineering can effectively modulate the band gap of WSe2/z-ZnO-NR. When the edge of z-ZnO-NR is not passivatied, the WSe2/z-ZnO-NR shows spin polarized band structure with a narrow gap. The band gap and spin polarization can be tuned by strain. The projected band structures reveal that the WSe2/z-ZnO-NR not only forms type-II band alignment, but also realizes the separation of different spin states. This work provides useful guide for designing photoelectronic devices experimentally.