Properties of B- and Si-doped monolayer black phosphorus under biaxial strain

Abstract

The properties of monolayer black phosphorus, B-doped black phosphorus and Si-doped black phosphorus under biaxial strain are studied by first-principles calculations. The computed bandgaps of black phosphorus and B-doped black phosphorus without strain are 0.92 eV and 0.61 eV, respectively. The bandgap of the monolayer black phosphorus increases to the maximum (1.09 eV) under the biaxial tensile strain of 2 %, and it decreases with the further increase of tensile strain. Under the biaxial compressive strain, the black phosphorus bandgap decreases all the time, and presents metallic characteristics when the compressive strain is −7%. For the B-doped monolayer black phosphorus, the bandgap increases to the maximum (0.71 eV) when the tensile strain is 4 %, but it decreases monotonically under the compressive strain. On the other hand, the Si-doped black phosphorus maintains metallic characteristics under tensile and compressive strains. The sub-bandgap absorption peaks of B-doped and Si-doped monolayer black phosphorus increase under biaxial compressive strain. For the B-doped monolayer black phosphorus, the sub-bandgap absorption range is extended to longer wavelength with the increase of compressive strain, and it can be extended to about 0.25 eV (4960 nm) under the −10 % compressive strain. The absorption range of Si-doped monolayer black phosphorus could be extended to far infrared under compressive strain. The research results have important guiding significance for the application of monolayer black phosphorus in photoelectric devices and nanomaterials.