  Phosphorene, a single layer of black phosphorous (BLK-P), has a significant
potential for flexible and tunable electronics, but attempts to grow it
epitaxially have been unsuccessful to date. Meanwhile, hexagonal blue
phoshorous (BL-P) has been achieved on closed-packed (111) metal surfaces in
special growth conditions of high vapor pressure and high reactivity of
phosphorous. The (111) surfaces favors BL-P over BLK-P due to its hexagonal
symmetry. Here, we investigate computationally the alternative offered by
stepped substrates. Using the Cu(311) surface as a model, we find that surface
steps can favor energetically BLK-P over BL-P. This can be rationalized in
terms of surface density of states and orbital hybridization, which lead to a
stronger surface bonding of the lower BLK-P half-layer. This work suggests that
vicinal metal surfaces of metals can offer a viable path towards phosphorene
synthesis.
