About the Interaction Between a Laser Beam and Group IV Nanowires: A Study of the Electromagnetic Field Enhancement in Homogeneous and Heterostructured Nanowires

Abstract

The optical properties of semiconductor nanowires (NWs) are object of study because they are the building blocks of the future nanophotonic devices. The high refractive index and its reduced dimension, make them suitable for photon engineering. The study of the interaction between NWs and visible light has revealed resonances of the light absorption/scattering by the NWs. Micro‐Raman spectroscopy is used as a characterization method of semiconductor NWs. The relation between the Raman intensity and the incident electromagnetic (EM) field permits to study the light/NW interaction through the micro‐Raman spectra of individual NWs. As compared to either metallic or dielectric NWs, the semiconductor NWs add additional tools to modify its interaction with light, for example, the composition, the presence of heterostructures, both axial and radial, doping, and the surface morphology. One presents herein a study of the optical response of group IV semiconductor NWs to visible photons. The study is experimentally carried out through the micro‐Raman spectroscopy of different group IV NWs, both homogeneous and heterostructured (SiGe/Si), and the results are analyzed in terms of the EM modeling of the light/NW interaction using finite element methods (FEMs). The heterostructures are seen to produce additional resonances allowing new photonic capacities to the semiconductor NWs.

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

“…In order to confirm this, a 2D laser scan of the NW was performed in order to study the role of the HJs with respect to the Raman signal of graphene. As shown in previous works, [26][27][28]32 the axial HJs give additional light absorption resonances enhancing the Raman signal with respect to the homogeneous segments of the NW. The results of the 2D scanning are summarized in Fig.…”

“…The model provides the 3D distribution of the EM field intensity, jEj 2 , which allows us to compute the expected Raman signal of each material since the Raman signal is proportional to the effective excitation light intensity. 27,28 The first measurements were performed on graphene/SiO 2 substrate, revealing a typical graphene Raman spectrum showing its characteristic Raman bands at 1580 cm À1 (G band) and 2700 cm À1 (2D band), 29 Fig. 1(a).…”