Phosphorus Pentamers: Floating Nanoflowers form a 2D Network

An experimental investigation of a new polymorphic 2D single layer of phosphorus on Ag(111) is presented. The atomically-resolved scanning tunneling microscopy images show a new 2D material composed of freely-floating phosphorus pentamers organized into a 2D layer, where the pentamers are aligned in close-packed rows. The scanning tunneling spectroscopy measurements reveal a semiconducting character with a band gap of 1.20 eV. This work presents the formation at low temperature of a new polymorphic 2D phosphorus layer composed of a floating 2D pentamer structure. The smooth curved terrace edges and a lack of any clear crystallographic orientation with respect to the Ag(111) substrate at room temperature indicates a smooth potential energy surface that is reminiscent of a liquid-like growth phase. This is confirmed by density functional theory calculations that find a small energy barrier of only 0.17 eV to surface diffusion of the pentamers (see Supporting Information). The formation of extended, homogeneous domains is a key ingredient to opening a new avenue to integrate this new 2D material into electronic devices.