From monolayer to lateral heterostructure of functionalized phosphorus carbide: Evolution of electronic properties

Abstract

Abstract Two-dimensional (2D) materials with semiconducting properties have attracted increasing research interest, but those having metallic character are not conducive to the application in nanodevices. As a novel metal-free 2D material, phosphorus carbide (PC) monolayer is greatly hampered to be useful in various fields by its metallic character. Herein, we propose effective strategies —— functionalizing, applying strain or constructing heterostructure —— to tune the electronic properties of PC from a monolayer to various lateral heterostructures. Using first-principles calculations, we report that hydrogenating/fluorinating at P (HPC/FPC) or C (PCH/PCF) atoms, or hydroxylating at P (HO-PC) atoms of PC monolayer results into a transition from metal to semiconductor. To further realize the evolution of electronic properties, three lateral heterostructures (LHS) (i.e., HPC-PCH, HPC-FPC, and HPC-HO-PC) are constructed by stitching two functionalized PC monolayers together. It is found that the electronic properties of HPC-PCH LHS depend on the size of heterostructure, and the band gap decreases with the width of LHS increasing. When stitching HPC with FPC or HO-PC, the semiconductor character retains and quasi-type II band alignment is observed in HPC-FPC, and zero-band offset type in HPC-HOPC at interface. Moreover, the electronic properties of LHSs can be modulated by applying strain: the band gap increases as applying 2% tensile, then decreases as applied tensile further increases; and transition between direct and indirect band gap is found as tensile increases, which all can be understood by the change of wave function distribution corresponding to high symmetry point in the first Brillouin zone. Tunability of electronic properties indicates that functionalized PC monolayer is a potential candidate for electronic, photovoltaic and photo response nanodevices.