Abstract
The ability to control light-matter interaction is central to several potential applications in lasing, sensing, and communication. Graphene plasmons provide a way of strongly enhancing the interaction and realizing ultrathin optoelectronic devices. Here, we find that photoluminescence (PL) intensities of the graphene/GeSi quantum dots hybrid structures are saturated and quenched under positive and negative voltages at the excitation of 325 nm, respectively. A mechanism called plasmon-gating effect is proposed to reveal the PL dependence of the hybrid structures on the external electric field. On the contrary, the PL intensities at the excitation of 405 and 795 nm of the hybrid structures are quenched due to the charge transfer by tuning the Fermi level of graphene or the blocking of the excitons recombination by excitons separation effect. The results also provide an evidence for the charge transfer mechanism. The plasmon gating effect on the PL provides a new way to control the optical properties of graphene/QD hybrid structures.
Highlights
The ability of enhancing light-matter interaction and localizing electromagnetic field of surface plasmons opens up opportunities for light manipulation on low-dimensional structures in a wide range of applications[1]
It has been found that graphene/ZnO hybrid structure produces an enhanced photoluminescence for the resonant surface plasmon-polariton (SPP) excitation of graphene in the emission stage[19]
We naturally consider whether the SPP enhanced PL properties of the graphene/GeSi quantum dots (QDs) hybrid structure can be controlled by introducing an external electric field
Summary
The ability of enhancing light-matter interaction and localizing electromagnetic field of surface plasmons opens up opportunities for light manipulation on low-dimensional structures in a wide range of applications[1]. We naturally consider whether the SPP enhanced PL properties of the graphene/GeSi QDs hybrid structure can be controlled by introducing an external electric field. It is considered whether the PL quenching, based on the carrier transfer or the energy transfer of excitons, can be directly indicated by tuning the graphene Fermi level with a bias voltage. The peculiar PL increasing and saturating characteristics are explained by a plasmon-gating mechanism, in which the graphene SPP with external electric field hinders the electrons to be transferred away from the surface of multilayer GeSi QDs structure and increases the number of excitons for the recombination. The PL results indicate that the graphene plasmon can be used to control the luminescence properties of semiconductor by the external vertical field
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