Regensburg 2007 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 28: Silicon Thin Films and Interfaces

DS 28.3: Vortrag

Freitag, 30. März 2007, 12:00–12:15, H32

Nanometer thick antireflection coating for infrared light — •Bruno Gompf, Jürgen Beister, Tobby Brandt, Jens Pflaum, and Martin Dressel — Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart

The optical properties of ultrathin Au films on silicon have been studied in the infrared over a wide frequency range from 200 cm⁻¹ to 10.000 cm⁻¹. Thick films show a Drude behavior, i.e. with increasing frequency the transmission gets better; for films below the percolation threshold (at about 5 nm) a negative slope for the frequency dependent transmission is observed. When the thickness is further reduced, between 1 and 3 nm an anomaly occurs: the relative transmission reaches maximum values above 100 % compared to the bare substrate, indicating an antireflection coating of nm thickness for light with 5 µm wavelength. This anomaly can be explained in the framework of effective medium theories.