Optical and Electrical Properties of Silver-Titanium Dioxide Layered Nanocomposites

Piotr Nyga Institute of Optoelectronics, Military University of Technology, Warsaw, Poland Sylwester Chmiel Institute of Optoelectronics, Military University of Technology, Warsaw, Poland Marzena Szczurek Institute of Optoelectronics, Military University of Technology, Warsaw, Poland Malwina Liszewska Institute of Optoelectronics, Military University of Technology, Warsaw, Poland Marek Stefaniak Institute of Optoelectronics, Military University of Technology, Warsaw, Poland Jozef Firak Institute of Optoelectronics, Military University of Technology, Warsaw, Poland Bartłomiej Jankiewicz Institute of Optoelectronics, Military University of Technology, Warsaw, Poland Malgorzata Norek Department of Advanced Materials and Technologies, Military University of Technology, Warsaw, Poland Jadwiga Mierczyk Institute of Optoelectronics, Military University of Technology, Warsaw, Poland

There is great interest in nanoscale metal-dielectric and metal-semiconductor structures and composites for their potential in many science and engineering fields. Various types of such nanostructures are studied for applications in sunlight harvesting processes like photovoltaics, photocatalysis, heat generation, but also for substrates for surface enhanced Raman and Infrared spectroscopies and many more. Most of the fabrication methods of nanostructures are relatively expensive considering cost per area, for example electron beam lithography. Physical vapor deposition (PVD) is one of the inexpensive methods of production of plasmonic metal nanostructures on surface or embedded in dielectric or semiconductor. When thin metal layer is deposited using PVD technique randomly arranged nanostructured semicontinuous metal film can be obtained. Size, shape and optical properties of these nanostructures can be controlled by choosing specific deposition process conditions. [1,2]

Here we present the details of optical and electrical properties of silver-titanium dioxide (Ag-TiO₂) layered nanocomposites fabricated using electron beam (EB) PVD technique. We varied several parameters of the fabricated structures and EB PVD process including silver and TiO₂ layer thickness, number of layers, deposition temperature, oxygen dosage and post fabrication annealing. Utilizing the semicontinuous nature of silver films we achieved structures with broadband absorption. The level and spectral width of absorption can be tuned by design. Through number of silver layers and their thickness the absorption level of composite can be adjusted from about 10% to above 90% in the visible and/or infrared range. We have also achieved control over composite sheet resistance, which will be reported along with its thermo-electric properties.

[1] P. Nyga, V.P. Drachev, M.D. Thoreson and V.M. Shalaev, “Mid-IR plasmonics and photomodification with Ag films,” Applied Physics B 93, 59-68 (2008).

[2] M.D. Thoreson, J. Fang, A.V. Kildishev, L.J. Prokopeva, P. Nyga, U.K. Chettiar, V.M. Shalaev and V.P. Drachev,” Fabrication and Realistic Modeling of 3D Metal-Dielectric Composites”, Journal of Nanophotonics 5, 051513-051513-17 (2011).

The research was financed by the Polish National Centre for Research and Development grant no LIDER/23/22/L-3/11/NCBR/2012.

pnyga@wat.edu.pl