Regensburg 2007 – scientific programme
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DS: Fachverband Dünne Schichten
DS 28: Silicon Thin Films and Interfaces
DS 28.3: Talk
Friday, March 30, 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.