Fabrication and plasmonic characterization of Au nanowires with controlled surface morphology

Fabrication And Plasmonic Characterization Of Au Nanowires With Controlled Surface Morphology

Ina Schubert^1*, Wilfried Sigle², Loic Burr^1,3, Peter A. van Aken², Christina Trautmann^{1, 3}, Maria Eugenia Toimil-Molares¹

¹Materials Research Department, GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany

²Stuttgart Center for Electron Microscopy, Max Planck Institute for Intelligent Systems, Stuttgart, Germany

³Department of Materials and Geo Science, Technische Universität Darmstadt, Darmstadt, Germany

Adv. Mater. Lett., 2015, 6 (5), pp 377-382

DOI: 10.5185/amlett.2015.5721

Publication Date (Web): May 05, 2015

E-mail: i.schubert@gsi.de

Full Article

Abstract

Gold nanowires are attracting great attention due to their ability to sustain surface plasmons and are thus promising candidates for sensing applications such as surface enhanced Raman and infrared spectroscopy. Controlling all nanowire parameters is crucial to adjust the resonance wavelengths and to obtain high electric field enhancements. We have fabricated Au nanowires with controlled dimensions and surface morphology by electro-deposition of Au and Au-Ag nanowires in the pores of ion-track-etched polymer templates. Smooth and rough nanowires are fabricated by the use of different polymer types. By dealloying of Au-Ag wires, porous Au wires are being created. In addition, we have analyzed the surface plasmonic properties of smooth and porous Au nanowires by scanning transmission electron microscopy combined with electron energy-loss spectroscopy. Our results reveal the excitation of five different longitudinal modes in the smooth as well as in the porous Au wire. The resonance energies of the porous wire are red-shifted compared to the energies of a smooth Au wire with same dimensions, which demonstrates that the surface morphology of the nanowire is an important parameter to tune the multipole surface plasmon modes to specific energies. Knowledge on the plasmonic properties of nanowires dependent on their surface morphology is indispensable for their efficient application for sensor technology.