Plasmon-Assisted Photoresponse in Ge-Coated Bowtie Nanojunctions
| Autor: | Kenneth M. Evans, Douglas Natelson, Pavlo Zolotavin |
|---|---|
| Rok vydání: | 2015 |
| Předmět: |
Photocurrent
Materials science Condensed Matter - Mesoscale and Nanoscale Physics business.industry Nanowire FOS: Physical sciences Physics::Optics Photothermal therapy Condensed Matter::Mesoscopic Systems and Quantum Hall Effect Polarization (waves) Atomic and Molecular Physics and Optics Electronic Optical and Magnetic Materials Amorphous solid Overlayer Condensed Matter::Materials Science Electrical resistivity and conductivity Mesoscale and Nanoscale Physics (cond-mat.mes-hall) Physics::Atomic and Molecular Clusters Optoelectronics Electrical and Electronic Engineering business Plasmon Physics - Optics Optics (physics.optics) Biotechnology |
| Zdroj: | ACS Photonics. 2:1192-1198 |
| ISSN: | 2330-4022 |
| DOI: | 10.1021/acsphotonics.5b00250 |
| Popis: | We demonstrate plasmon-enhanced photoconduction in Au bowtie nanojunctions containing nanogaps overlaid with an amorphous Ge film. The role of plasmons in the production of nanogap photocurrent is verified by studying the unusual polarization dependence of the photoresponse. With increasing Ge thickness, the nanogap polarization of the photoresponse rotates 90 degrees, indicating a change in the dominant relevant plasmon mode, from the resonant transverse plasmon at low thicknesses to the nonresonant "lightning rod" mode at higher thicknesses. To understand the plasmon response in the presence of the Ge overlayer and whether the Ge degrades the Au plasmonic properties, we investigate the photothermal response (from the temperature-dependent Au resistivity) in no-gap nanowire structures, as a function of Ge film thickness and nanowire geometry. The film thickness and geometry dependence are modeled using a cross-sectional, finite element simulation. The no-gap structures and the modeling confirm that the striking change in nanogap polarization response results from redshifting of the resonant transverse mode, rather than degradation in the Au/Ge properties. We note remaining challenges in determining the precise mechanism of photocurrent production in the nanogap structures. Comment: 20 pages, 5 figures |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|