Electronic and Optical Properties of monolayer boron nitride on a graphite substrate*

In this work, we investigate the electronic and optical properties of monolayer boron nitride (mBN) grown on Highly Ordered Pyrolytic Graphite (HOPG) substrate based on density functional theory and many-body perturbation theory. Our results indicate that the screening of the semi-metallic graphite substrate results in a giant bandgap renormalization of mBN. Also, we find a huge reduction of exciton binding energy in the presence of HOPG substrate and a blue-shifting of the 1s-exciton energy to above 6 eV. Furthermore, we demonstrate that strong electron–phonon interactions also play an important role in the optical process of mBN and give rise to the multiple phonon sidebands as observed from photoluminescence measurements. As a result, we propose that both the strong dielectric screening from the substrate and the strong electron–phonon interaction must be explicitly included to the analysis of luminescence measurements.