Excitons under strain: light absorption and emission in strained hexagonal boron nitride

Abstract

Hexagonal boron nitride is an indirect band gap material with a strong luminescence intensity in the ultraviolet. This luminescence originates from bound excitons recombination assisted by different phonon modes. The coupling between excitons and phonons is so strong that the resulting light emission is as efficient as the one of direct band gap materials. In this manuscript we investigate how uniaxial strain modifies the properties of this material. In particular we study how the electronic band structure and optical response change with strain. Our results are important for experiments that directly probe h-BN under strain or use it as substrate for other 2D material with a lattice mismatch.