Collective excitations in gapped graphene-GaAs double-layer structures

Abstract

The aim of this work is to determine the collective excitations and decay rate of plasma oscillations in a gapped graphene-GaAs double-layer structure within random phase approximation without temperature effects. Firstly, we utilize long wavelength approximation expansions of polarization functions and Coulomb bare interactions to observe the analytical expressions for plasmon frequencies. These analytical formulae demonstrate that the band gap has significant contributions to collective excitations. Secondly, our numerical calculations illustrate that in-phase optical plamon branch continues in single-particle excitation area while acoustic out-of-phase one merges into the boundary of this area then disappears. Besides, taking into account the band gap decreases remarkably optical plasmon frequency meanwhile carrier density affects on acoustic branch, dissimilar to that in other double-layer structures. Finally, the interlayer separation and the inhomogeneous dielectric environment affect on both plasmon modes, similar to those obtained in previous works.