On the elasticity and piezoelectricity of black(blue) phosphorus/ZnO van der Waals heterostructures

Using density functional theory based calculations, we systematically determined the structural, elastic, electronic and piezoelectric properties of layered heterostructures consisting of black(blue) phosphorous and zinc oxide monolayers, i.e., BlackP/ZnO and BlueP/ZnO. The van der Waals interaction was carefully taken into account in all calculations. It was found that the elastic moduli of the layered heterostructures are significantly enhanced comparing with those of each constituent monolayer. The BlackP/ZnO heterostructure belongs to type-I with the direct band gap of 1.49 eV while the BlueP/ZnO one is type-II with the indirect band gap of 1.92 eV. Both were calculated by the Heyd-Scuseria-Ernzerhorf hybrid functional. The piezoelectric response also gets enhanced by constructing the BlackP/ZnO heterostructure while it does not change much for the BlueP/ZnO case. Our findings may provide a great opportunity to design better piezoelectric devices based on such layered heterostructures at nanoscale.