The authors present a second-generation broadband 4×4 Mueller-matrix (MM) ellipsometer for ultrasensitive infrared-spectroscopic (8000−800cm−1) studies of complex nanometer-thin films. In a modular design, the instrument employs retractable achromatic retarders and various sets of tandem polarizers. Using high-transmittance free-standing wire-grid polarizers, the device reaches an unparalleled precision of up to 5⋅10−5 in the important fingerprint region, even for block-offdiagonal MM elements. Broadband and signal-to-noise optimized access to the full 4×4 MM provides in-depth information on the sample’s polarimetric properties and opens the door for detailed explorations of depolarizing and anisotropic materials. The authors discuss examples of highly depolarizing nonuniform polyimide membranes, uniaxial-to-biaxial anisotropy changes in ultrathin polymer films, and azimuthal off-axis effects in 2D-structured silica arrays. Diverse optical modeling approaches based upon anisotropic layer stacks and rigorous coupled-wave analysis are used to quantify the optical, structural, and chemical properties of the sample.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): BAS/1/1323-01-01
Acknowledgements: The authors are indebted to Matthias Zellmeier (HZB Berlin) for the preparation of the trapezoidal SiO2 arrays, to Timur Shaykhutdinov for expertise in RCWA simulations, to Uwe Richter (Sentech Instruments GmbH), as well as Ilona Engler, Cordula Walder, and Özgür Savaş for technical assistance, to Margarita Günther (TU Dresden) and Karin Sahre and Klaus-Jochen Eichhorn (IPF Dresden) for providing the PI2611 samples, and to Sentech Instruments GmbH for construction of the retarder units. Financial support through European Union grants (EFRE 1.8/13, ProFIT Nos. 10160255, 10160265, and 10160256) as well as by the Ministerium für Innovation, Wissenschaft und Forschung des Landes Nordrhein-Westfalen, the Regierende Bürgermeister von Berlin—Senatskanzlei Wissenschaft und Forschung, and the Bundesministerium für Bildung und Forschung is gratefully acknowledged. I.P. acknowledges support from KAUST (baseline funding No. BAS/1/1323-01-01)