Abstract
Single-layer black phosphorous (BP), or phosphorene, is a highly-anisotropic
two-dimensional elemental material possessing promising semiconductor properties
for flexible electronics. However, the direct bandgap of single-layer black
phosphorus predicted theoretically has not been directly measured, and the
properties of its edges have not been considered in detail. Here we report atomic
scale electronic variation related to strain-induced anisotropic deformation of the
puckered honeycomb structure of freshly cleaved black phosphorus using a highresolved
scanning tunneling spectroscopy (STS) survey along the light (x) and heavy
(y) effective mass directions. Through a combination of STS measurements and
first-principles calculations, a model for edge reconstruction is also determined. The
reconstruction is shown to self-passivate any dangling bond by switching the
oxidation state of phosphorous from +3 to +5.
