Optical Phonon Modes in Rectangular Graphene Quantum Dots

Recently, graphene has been studied extensively as a promising material for future high-performance electronics. Dimensionally-confined graphene nanostructures are building blocks of devices and the carrier-phonon interactions in these device structures are frequently critical to their electronic properties. For a two-dimensional confined graphene nanosheet with orthogonal in-plane boundaries along armchair and zigzag edge, the confined carrier and optical phonon states are determined. The electron-longitudinal optical (LO)-phonon interactions in these graphene quantum dots are studied by the optical deformation potential theory. Phonon bottleneck effects are found for general graphene quantum dots. Carrier-LO-phonon scattering events are allowed only for graphene quantum dots with certain sizes; Fermi golden rule transition rates are evaluated approximately for cases where the dot dimensions are such that transitions are allowed.