Tuning optical properties of monolayer hexagonal boron nitride induced by bi-axial strain

We report the influence of bi-axial tensile mechanical strain in the range 0-15% on the band-structures and absorption spectra of monolayer hexagonal boron nitride (h-BN). First of all, we employ density functional theory to extract the ground state band-structures and see a gradual decrease of 1.054 eV in the band-gap with increase in strain from 0-15%. Many body perturbation theory is used to calculate quasi-particle band-structure and the absorption spectra peak which is found to decrease linearly with the applied strain by 1.9 eV when moving from 0-15%. There is no direct to indirect transition due to the applied strain but the second excitonic peak shows decrease in its strength as the strain increases. Also, a red shift is seen in the absorption spectra as the strain increases moving from 246 nm to 354 nm in wavelength, validating that strain engineering persist to be an efficient tool to tune the opto-electronic properties of monolayer h-BN.