title: Electronic bandgap and edge reconstruction in phosphorene materials.
abstract: Single-layer black phosphorus (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 high-resolution 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 most dangling bonds by switching the coordination number of phosphorus from 3 to 5 or 3 to 4.
authors.affiliation: Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute , Troy, New York 12180, United States.
authors.forename: Liangbo
authors.initials: L
authors.lastname: Liang
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.forename: Wenzhi
authors.initials: W
authors.lastname: Lin
authors.forename: Bobby G
authors.initials: BG
authors.lastname: Sumpter
authors.forename: Vincent
authors.initials: V
authors.lastname: Meunier
authors.forename: Minghu
authors.initials: M
authors.lastname: Pan
keywords: Phosphorene; density functional theory; direct bandgap; monatomic step edges; scanning tunneling microscopy/spectroscopy; self-passivation