Local electric field enhancement at the heterojunction of Si/SiGe axially heterostructured nanowires under laser illumination

Journal of Applied Physics

Anaya

Souto

et al. 2018

Semiconductor nanowires (NWs) are the building blocks of future nanoelectronic devices. Furthermore, their large refractive index and reduced dimension make them suitable for nanophotonics. The study of the interaction between nanowires and visible light reveals resonances that promise light absorption/scattering engineering for photonic applications. Micro-Raman spectroscopy has been used as a characterization tool for semiconductor nanowires. The light/nanowire interaction can be experimentally assessed through the micro-Raman spectra of individual nanowires. As compared to both metallic and dielectric nanowires, semiconductor nanowires add additional tools for photon engineering. In particular, one can grow heterostructured nanowires, both axial and radial, and also one could modulate the doping level and the surface condition among other factors than can affect the light/NW interaction. We present herein a study of the optical response of group IV semiconductor nanowires to visible photons. The study is experimentally carried out through micro-Raman spectroscopy of different group IV nanowires, both homogeneous and axially heterostructured (SiGe/Si). The results are analyzed in terms of the electromagnetic modelling of the light/nanowire interaction using finite element methods. The presence of axial heterostructures is shown to produce electromagnetic resonances promising new photon engineering capabilities of semiconductor nanowires.

Section: A Axially Heterostructured Nwscontrasting

confidence: 53%

“…2 of Ref. 39. One observes the typical Raman spectrum of a Si NW for the laser beam focused on the Si segment.…”

Section: A Axially Heterostructured Nwsmentioning

confidence: 93%

Electromagnetic field enhancement effects in group IV semiconductor nanowires. A Raman spectroscopy approach

Journal of Applied Physics

Anaya

Souto

et al. 2018

“…This model is solved by FEMs using COMSOL Multiphysics. The Maxwell equations are solved for the NW and its surrounding space when excited by a focused laser beam in similar conditions to the micro‐Raman experiments . The system formed by the air/NW/substrate was limited by cartesian perfectly matched layers (PMLs), which absorb the outgoing radiation eliminating secondary reflections, Figure .…”

Section: Resultsmentioning

confidence: 99%

“…The presence of the axial heterojunction breaks the longitudinal symmetry of the NW. Therefore, a 3D model must be applied, instead of the 2D model used for NWs without axial discontinuities, either homogeneous NWs or core/shell heterostructured NWs . The 3D model accounts for the presence of the axial HJ; and also takes account of the finite length of the NW.…”

Section: Resultsmentioning

confidence: 99%

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

Physica Status Solidi (a)

Anaya

Jiménez

2018

Self Cite

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.

“…The enhancement effect in these NWs with a greater Ge composition ($ 60% Ge) is more intense than that observed in NWs with lower Ge composition. 8 Moreover, due to the higher Ge composition of the NWs, the Raman bands are clearly separated and there is no need for a deconvolution of the Raman spectra.…”

Section: Resultsmentioning

confidence: 99%

Electromagnetic Field Enhancement on Axially Heterostructured NWs: The Role of the Heterojunctions

Souto

Periwal

et al. 2018

Journal of Elec Materi

Semiconductor nanowires are the building blocks of future nanoelectronic devices. The study of the interaction between nanowires and visible light reveals resonances that promise light absorption/scattering engineering for photonic applications. We carried out experimental measurements through the micro-Raman spectroscopy of different group IV nanowires, both homogeneous Si nanowires and axially heterostructured SiGe/Si nanowires. These experimental measurements show an enhancement of the Raman signal in the vicinity of the heterojunction of SiGe/Si nanowires. The results are analysed in terms of the electromagnetic modelling of the light/nanowire interaction using finite element methods. The presence of axial heterostructures is shown to produce electromagnetic resonances, and the results are understood as a consequence of a finite change in the relative permittivity of the material at the SiGe/Si heterojunction. This effect opens a path to controlling interactions between light and matter at the nanoscale with direct applications in photonic nanodevices.