First-principles studies of the strain-induced band-gap tuning in black phosphorene.

Using first-principles calculations, we have studied the band-gap modulation as function of applied strain in black phosphorene (BP). Dynamical stability has been assessed as well. Three cases have been considered, in the first and second, the strain was applied uniaxially, in thex- andy-axis, separately. In the third, an isotropic in-plane strain was analyzed. Different strain percentages have been considered, ranging from 4% to 20%. The evolution of the band-gap is studied by using standard DFT and the G0W0approach. The band-gap increases for small strains but then decreases for higher strains. A change in electronic behavior also takes place: the strained systems change from direct to indirect band-gap semiconductor, which is explained in terms of thesandp-orbitals overlap. Our study shows that BP is a system with a broad range of applications: in band-gap engineering, or as part of van der Waals heterostructures with materials of larger lattice parameters. Its stability, and direct band-gap behavior are not affected for less than 16% of uniaxial and biaxial strain. Our findings show that phosphorene could be deposited in a large number of substrates without losing its semiconductor behavior.