Scattering of microwaves in thin metallic films near the metal - non-metal transition

Jan Obrzut

Abstract

We present measurements demonstrating significant scattering of microwaves in thin metal films near the metal – non-metal percolation transition. Gold films 3 nm to 12 nm thick were characterized using patterned coplanar waveguides over a frequency range of 100 MHz to 20 GHz. Within the percolation coverage of gold nanoparticles when conductivity > 5 x 103 S/cm and the film properties transition from the dielectric to metallic, the microwave transmittance falls far more rapidly than the classical skin depth model would suggest. We observe a frequency-independent absorption peak of about 50 % in that range, which we believe results from an inhomogeneous localization of electromagnetic field, with no characteristic length scale. Our results demonstrate new techniques to study mechanisms of electromagnetic response of randomly structured metallic networks, and suggests the possibility of using surface-enhanced thin films for microwave applications.

Keywords

microwave propagation; gold nanoparticles; metal-dielectric transition; percolation transition; coplanar waveguides

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DOI

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IMEKO TC

TC4 - Measurement of Electrical Quantities

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