3D field confinement in the near-field interaction between graphene and Si/SiGe axially heterostructured NWs

Interest in the integration of graphene and semiconductor nanowires (NWs) increased dramatically during the last two decades along with the overwhelming development of graphene technology. The possibility of combining the countless properties of graphene with the singular optical behavior of semiconductor NWs leads the way to the design of unique photonic nanodevices. In this work, the optical response of Si/SiGe axially heterostructured NWs deposited over a graphene monolayer is investigated. The results demonstrate the enhancement of the graphene Raman signal under the influence of the NW. Moreover, the presence of an axial heterojunction in the NW is shown to locally hinder this enhancement through the full confinement of the incident electromagnetic field inside the NW body around the heterojunction. This complex interaction could be the basis for near-field probes for molecules or 2D materials, and optoelectronic devices including graphene/NW interfaces.