Berlin 2018 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 47: Poster Session II

MM 47.45: Poster

Mittwoch, 14. März 2018, 18:30–19:45, Poster C

Terahertz Spectroscopy of thin metallic films — •Natalie Kattner, Nathan Jukam, and Andreas Wieck — Angewandte Festkörperphysik, Ruhr-Universität Bochum, Universitätsstraße 150, D-44780 Bochum

In the last decades new Terahertz (THz) sources have been developed. Many terahertz devices such as plasmonic waveguides for THz quantum cascade lasers (QCL) cavities, photonic crystals or planar meta-material resonators incorporate metals, since they have relatively low losses and high reflectivities at terahertz frequencies.

The complex conductivity of a metal determines losses in devices. In many devices thin metallic films are used in lieu of bulk-materials. The conductivity of the thin films is in general not equal to the bulk conductivity. Thus, there has been much confusion as to the proper conductivity values and the validity of the Drude model.

Here, we examine the complex conductivity of thin films of Gold, Aluminum and Copper at terahertz frequencies in a temperature range from 4K to room temperature with Time-Domain Spectroscopy (TDS). From the TDS spectrum we determine the complex conductivity. In addition, we measure the DC conductivity of thin films as a function of temperature.

The advantages of TDS are the generation of coherent light and the possibility to determine the amplitude and the phase of the electromagnetic field. Consequently, the complex conductivity can either be determined from the reflection or the transmission coefficients without using the Kramers-Kronig relations.