Dresden 2017 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 28: Plasmonics and Nanooptics IV: Light-Matter Interaction
O 28.7: Vortrag
Dienstag, 21. März 2017, 12:00–12:15, TRE Ma
Near-field investigation of geometric and material resonances in semiconductor nanowires with doped segments — •Lena Jung1, Dmitriy S. Boyuk2, Amar T. Mohabir2, Michael A. Filler2, and Thomas Taubner1 — 1I. Institute of Physics (IA), RWTH Aachen University, 52056 Aachen, Germany — 2School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
Doped semiconductors (SCs) allow for tunability of plasmon resonances via gating or doping. We investigate Si nanowires (NWs) with doped segments with infrared near-field microscopy (s-SNOM). In s-SNOM, optical near-fields that are excited via laser-illumination of a metalized AFM tip interact with the sample. This enables to determine the samples dielectric properties with a high resolution only limited by the tip radius (∼25 nm). By combining the Drude model for doped SCs with models for the tip-sample interaction, carrier properties of the doped SC can be obtained by spectroscopic imaging in the range of a near-field resonance close to the plasma edge. Additionally, the doped segments in the NWs act as resonators for mid-IR light due to their geometry. Localized surface plasmon (LSP) resonances have been observed in the far-field. Different growth conditions revealed differences in the shape of the spectra, explained by variations in the sharpness of the segment boundaries [1]. Goal of our investigations is to distinguish these different effects and to determine carrier properties, boundary sharpness and map the LSP resonance given by the segment geometry.
[1] Chou et al., ACS Nano 9, 1250 (2015)