Strain induced tunable band gap and optical properties of graphene on hexagonal boron nitride

Abstract In this study, we highlight the potential of strain engineering in graphene/hexagonal boron nitride (hBN) 2D heterostructures, enabling their use as wide-range light absorbers with significant implications for optoelectronic applications. We systematically investigate the electronic and optical properties of graphene/hBN under the application of strain, considering various stacking geometries within the framework of density-functional theory. The semimetallic graphene layer upon aligning on the insulating hBN sheet opens a few tens of meV band gap at the Dirac point caused by the breaking of sublattice symmetry through induced on-site energy variations. Here, we demonstrate that by simultaneously tuning the interlayer distance and lattice constant, this band gap can be significantly increased to 1 eV. Interestingly, in both scenarios (small and large band gaps), the material undergoes a transition from a semiconductor to a narrow gap state. Importantly, the tunability of this band gap is strongly influenced by the specific stacking configuration. We further explored the optical properties across a broad spectrum, revealing that the presence of a strain-induced band gap fundamentally alters how light interacts with the system.