Berlin 2018 – scientific programme

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DS: Fachverband Dünne Schichten

DS 17: Poster Session I

DS 17.50: Poster

Tuesday, March 13, 2018, 18:15–20:15, Poster B

Infrared Mueller Ellipsometry of Thin Films — •Andreas Furchner, Cordula Walder, and Karsten Hinrichs — Leibniz-Institut für Analytische Wissenschaften -- ISAS -- e.V., Schwarzschildstraße 8, 12489 Berlin, Germany

Non-isotropic thin films can be characterized by their Mueller matrix (MM), a 4x4 matrix that describes the sample's optical properties upon interaction with polarized light. Besides anisotropy and structure, Mueller matrices in the infrared region provide information on, for example, film chemistry, composition, and molecular interactions. However, laboratory thin-film MM measurements in the infrared are inherently difficult, in part because of source prepolarization, non-ideal polarizers, and low optical throughput.

We developed a powerful IR Mueller ellipsometer with high optical throughput that enables sensitive MM measurements of thin films below 100 nm. The measurement scheme can be restricted to a subset of defined polarizer settings, allowing one to extract quadruples of Mueller matrix elements within a few 10 seconds to minutes. Tandem polarizers gurantee a sufficiently high degree of polarization necessary to accurately measure block-offdiagonal MM elements, while optional retarders provide access the fourth row or column of the Mueller matrix. Both normalized and absolute Mueller matrices can be obtained.

We demonstate Mueller matrix measurements of thin polymer films and, in cooperation with HZB Berlin, of trapezoidal SiO2 gratings, the offdiagonal MM elements of which are highly sensitive towards structure and orientation.