Anisotropy of 3D Columnar Coatings in Mid-Infrared Spectral Range
Lina Grineviciute,
Soon Hock Ng,
Molong Han,
Tania Moein,
Vijayakumar Anand,
Tomas Katkus,
Meguya Ryu,
Junko Morikawa,
Mark J. Tobin,
Jitraporn Vongsvivut,
Tomas Tolenis,
Saulius Juodkazis
Affiliations
Lina Grineviciute
Center for Physical Sciences and Technology, Savanoriu̧ Ave. 231, LT-02300 Vilnius, Lithuania
Soon Hock Ng
Optical Sciences Centre and ARC Training Centre in Surface Engineering for Advanced Materials (SEAM), School of Science, Swinburne University of Technology, Hawthorn, VIC 3122, Australia
Molong Han
Optical Sciences Centre and ARC Training Centre in Surface Engineering for Advanced Materials (SEAM), School of Science, Swinburne University of Technology, Hawthorn, VIC 3122, Australia
Tania Moein
Optical Sciences Centre and ARC Training Centre in Surface Engineering for Advanced Materials (SEAM), School of Science, Swinburne University of Technology, Hawthorn, VIC 3122, Australia
Vijayakumar Anand
Optical Sciences Centre and ARC Training Centre in Surface Engineering for Advanced Materials (SEAM), School of Science, Swinburne University of Technology, Hawthorn, VIC 3122, Australia
Tomas Katkus
Optical Sciences Centre and ARC Training Centre in Surface Engineering for Advanced Materials (SEAM), School of Science, Swinburne University of Technology, Hawthorn, VIC 3122, Australia
Meguya Ryu
Research Institute for Material and Chemical Measurement, National Metrology Institute of Japan (AIST), Tsukuba Central 3, 1-1-1 Umezono, Tsukuba 305-8563, Japan
Junko Morikawa
CREST—JST and School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1, Ookayama, Meguro-ku, Tokyo 152-8550, Japan
Center for Physical Sciences and Technology, Savanoriu̧ Ave. 231, LT-02300 Vilnius, Lithuania
Saulius Juodkazis
Optical Sciences Centre and ARC Training Centre in Surface Engineering for Advanced Materials (SEAM), School of Science, Swinburne University of Technology, Hawthorn, VIC 3122, Australia
Polarisation analysis in the mid-infrared fingerprint region was carried out on thin (∼1 μm) Si and SiO2 films evaporated via glancing angle deposition (GLAD) method at 70∘ to the normal. Synchrotron-based infrared microspectroscopic measurements were carried out on the Infrared Microspectroscopy (IRM) beamline at Australian Synchrotron. Specific absorption bands, particularly Si-O-Si stretching vibration, was found to follow the angular dependence of ∼cos2θ, consistent with the absorption anisotropy. This unexpected anisotropy stems from the enhanced absorption in nano-crevices, which have orientation following the cos2θ angular dependence as revealed by Fourier transforming the image of the surface of 3D columnar films and numerical modeling of light field enhancement by sub-wavelength nano-crevices.
