Numerical Study of Graphene Superlattice-Based Photodetectors

The optical properties of 1-D superlattices formed by armchair graphene nanoribbons embedded in hexagonal boron nitride superlattices (BNSLs) are studied. A set of tight-binding (TB) parameters is proposed, which gives results in excellent agreement with first-principle calculations. Based on the tight-binding model, it is demonstrated that in BNSLs, a larger bandgap opening is achieved than in hydrogen-passivated superlattices (HSL). The optical properties of BNSL and HSL are studied by employing the nonequilibrium Green function method and are verified with first-principle calculations. The role of line-edge roughness on the optical properties of such devices is carefully investigated.