Interlayer Excitons at h-BN/Diamond Heterostructures*

Hexagonal boron nitride is an ultra-wide-bandgap material and has gained much interest due to its strong excitonic effects. Especially, properties such as the exciton binding energy and lifetime are known to be strongly influenced by the choice of the substrate. A suitable substrate is diamond (111) due to the small lattice mismatch with h-BN. Therefore, monolayer h-BN can be directly grown or transferred into a diamond (111). Due to the negative electron affinity of diamond(111), the heterostructure shows a type-II band alignment, meaning that the formation of the interlayer excitons is expected for the heterostructure. These interlayer excitons are expected to show prolonged lifetime and room-temperature stability, which are required features for excitonic applications. In this study, we investigate the electronic, optical, and excitonic properties of the mBN-diamond heterostructure. DFT calculations are performed within Quantum Espresso, and subsequent GW and BSE calculations are performed within BerkeleyGW. Our results shed light on the luminescence and lifetime properties of interlayer excitons formed at the interface between these two important materials.