Optical Tunable Moire Excitons in Twisted Hexagonal GaTe Bilayers

Optical fine-tunable layer-hybridized Moire excitons are highly in demand for emerging many-body states in two-dimensional semiconductors. We report naturally confined layer-hybridized bright Moire excitons with long lifetimes in twisted hexagonal GaTe bilayers, using ab initio many-body perturbation theory and the Bethe-Salpeter equation. Due to the hybridization of electrons and holes between layers, which enhances the brightness of excitons, the twisted bilayer system becomes attractive for optical applications. We find that in both R and H-type stacking Moire superlattices, more than 200 meV lateral quantum confinements occur on exciton energies, which results in two scenarios: (1) The ground state bright excitons X-A are found to be trapped at two high-symmetry points, with opposite electric dipoles in the R-stacking Moire supercell, forming a honeycomb superlattice of nearest-neighbor dipolar attraction. (2) For H-stacking case, the X-A is found to be trapped at only one high-symmetry point exhibiting a triangular superlattice. Our results suggest that twisted h-GaTe bilayer is one of the promising systems for optical fine-tunable excitonic devices and provide an ideal platform for realizing strong correlated Bose-Hubbard physics.