title: Nanoporous Gold Nanoparticles and Au/Al2O3Hybrid Nanoparticles with Large Tunability of Plasmonic Properties.
abstract: Nanoporous gold nanoparticles (NPG-NPs) with controlled particle size and pore size are fabricated via a combination of solid-state dewetting and a subsequent dealloying process. Because of the combined effects of size and porosity, the NPG-NPs exhibit greater plasmonic tunability and significantly higher local field enhancement as compared to solid NPs. The effects of the nanoscale porosity and pore size on the optical extinction are investigated for the NPG-NPs with different particle sizes experimentally and theoretically. The influences of both porosity and pore size on the plasmonic properties are very complicated and clearly different for small particles with dominated dipole mode and large particles with dominated quadrupole mode. Au/Al2O3hybrid porous NPs with controlled porosity and composition ratio are fabricated through plasma-enhanced atomic layer deposition of Al2O3into the porous structure. In the Au/Al2O3hybrid porous NPs, both Au and Al2O3components are bicontinuously percolated over the entire structure. A further red shift of the plasmon peak is observed in the hybrid NPs due to the change of the environmental refractive index. The high tunability of the plasmonic resonances in the NPG-NPs and the hybrid porous NPs can be very useful for many applications in sensing biological and organic molecules.
authors.affiliation: Group Materials for Electronics, Institute of Materials Engineering and Institute of Micro- and Nanotechnologies MacroNano®, Technische Universität Ilmenau , Gustav-Kirchhoff-Str. 5, 98693 Ilmenau, Germany.
authors.forename: Wenye
authors.initials: W
authors.lastname: Rao
authors.affiliation: Group Materials for Electronics, Institute of Materials Engineering and Institute of Micro- and Nanotechnologies MacroNano®, Technische Universität Ilmenau , Gustav-Kirchhoff-Str. 5, 98693 Ilmenau, Germany.
authors.forename: Dong
authors.identifier: http://orcid.org/0000-0001-5940-9538
authors.initials: D
authors.lastname: Wang
authors.affiliation: Group Materials for Electronics, Institute of Materials Engineering and Institute of Micro- and Nanotechnologies MacroNano®, Technische Universität Ilmenau , Gustav-Kirchhoff-Str. 5, 98693 Ilmenau, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Kups
authors.affiliation: Department of Solid State Physics, University of Debrecen , P.O. Box 2, H-4010 Debrecen, Hungary.
authors.forename: Eszter
authors.initials: E
authors.lastname: Baradács
authors.affiliation: Department of Solid State Physics, University of Debrecen , P.O. Box 2, H-4010 Debrecen, Hungary.
authors.forename: Bence
authors.initials: B
authors.lastname: Parditka
authors.affiliation: Department of Solid State Physics, University of Debrecen , P.O. Box 2, H-4010 Debrecen, Hungary.
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Erdélyi
authors.affiliation: Group Materials for Electronics, Institute of Materials Engineering and Institute of Micro- and Nanotechnologies MacroNano®, Technische Universität Ilmenau , Gustav-Kirchhoff-Str. 5, 98693 Ilmenau, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Schaaf
keywords: hybrid; nanoparticle; nanophotonics; nanoporous gold; plasmon resonance