Millivolt Modulation of Plasmonic Metasurface Optical Response via Ionic Conductance

• Published in: Advanced materials (Weinheim) Vol. 29; no. 31
• Main Authors: Thyagarajan, Krishnan, Sokhoyan, Ruzan, Zornberg, Leonardo, Atwater, Harry A.
• Format: Journal Article
• Language: English
• Published: United States Wiley 14.06.2017
• Subjects: filament formation; indium tin oxide (ITO); ionic transport; MATERIALS SCIENCE; memristors; tunable metasurfaces
• ISSN: 0935-9648; 1521-4095

A plasmonic metasurface with an electrically tunable optical response that operates at strikingly low modulation voltages is experimentally demonstrated. The fabricated metasurface shows up to 30% relative change in reflectance in the visible spectral range upon application of 5 mV and 78% absolute change in reflectance upon application of 100 mV of bias. The designed metasurface consists of nanostructured silver and indium tin oxide (ITO) electrodes which are separated by 5 nm thick alumina. The millivolt-scale optical modulation is attributed to a new modulation mechanism, in which transport of silver ions through alumina dielectric leads to bias-induced nucleation and growth of silver nanoparticles in the ITO counter-electrode, altering the optical extinction response. This transport mechanism, which occurs at applied electric fields of 1 mV nm-1, provides a new approach to use of ionic transport for electrical control over light–matter interactions.