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Surface conductance and microwave scattering in semicontinous gold films



Jan Obrzut


Semicontinous gold films 4 nm to 12 nm thick were characterized using patterned coplanar waveguides over a frequency range of 100 MHz to 20 GHz. Such films can form two dimensional fractal aggregates mixed with dielectric voids with unusually large electromagnetic absorption. Surface conductance and microwave absorption were obtained from the measured scattering parameters using a microwave transmission-reflection model. Within the percolation coverage of gold nanoparticles, the surface conductance increases from 1.510–5 S/sq to1210–3 S/sq, the film properties transition from dielectric to metallic, and the corresponding microwave transmittance falls far more rapidly than the classical skin depth model would suggest. The resulting microwave absorption attains a peak value of about 50 % in this range, which we believe results from an inhomogeneous localization of an electromagnetic field in fractal structures, with no characteristic length scale. In the limit of full coverage and film thickness of 15 nm, the surface conductance approaches the value of 0.6 S/sq, which corresponds to volume conductivity of bulk metallic gold of about 4 107 S/m. The results demonstrate a convenient measurement technique to study mechanisms of electromagnetic response from surface-enhanced thin metallic films for microwave application


microwave measurements, metallic nanoparticles, semicontinouous metallic films, surface conductance, microwave absorption.


Obrzut, J. (2015), Surface conductance and microwave scattering in semicontinous gold films, ACTA IMEKO, [online], (Accessed April 23, 2024)
Created September 28, 2015, Updated November 10, 2018