Dirac Fermions in Blue Phosphorene Monolayer
Abstract
2D materials beyond graphene and in particular 2D semiconductors have
raised interest due to their unprecedented electronic properties, such as high
carrier mobility or tunable bandgap. Blue phosphorene is an allotrope of black
phosphorene that resembles graphene as it presents a honeycomb structure.
However, it is known to have semiconductor character and the crucial point
is to determine whether this hexagonal phase of phosphorene presents Dirac
fermions as in graphene. Here, the first compelling experimental evidence
of Dirac fermions in blue phosphorene layer grown on Cu(111) surface is
presented. The results highlight the formation of a highly ordered blue
phosphorene sheet with a clear Dirac cone at the high symmetry points of the
Brillouin Zone. The charge carriers behave as massless relativistic particles.
Therefore, all the expectations held for graphene, such as high-speed electronic
devices based on ballistic transport at room temperature, may also be
applied to blue phosphorene.