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DS: Fachverband Dünne Schichten
DS 13: Layer Deposition II: Deposition Methods
DS 13.3: Vortrag
Montag, 16. März 2020, 17:15–17:30, CHE 89
Atomic layer deposition of optical coatings on PMMA — •Pallabi Paul1, Kristin Pfeiffer2, and Adriana Szeghalmi1,2 — 1Institute of Applied Physics, Abbe Centre of Photonics, Friedrich Schiller University Jena, Germany — 2Fraunhofer Institute for Applied Optics and Precision Engineering, Jena, Germany
Atomic layer deposition (ALD), based on self-saturating surface reactions, is a promising chemical coating technology due to its conformal film growth on complex shaped substrates. Thermoplastics like poly(methyl methacrylate) (PMMA) is an important alternative to glass optics and has widely been used in producing various optical components. However, precision coatings on plastics are rather challenging due to the tendency of crack formation and typically low adhesion of the dielectric coatings to the polymer surface. Thus, materials and processes need to be tuned to the particularities of specific polymer. In this work, optimization of ALD processes to develop uniform, homogeneous and dense optical thin films of Al2O3, TiO2 and SiO2 on PMMA has been carried out and a five-layer antireflection coating is demonstrated. While uncoated PMMA substrates have a reflectance of nearly 8% in the visible spectral range, the reflectance of double-sided antireflection coating does not exceed 1.2% in the spectral range of 420 nm to 670 nm with a total average reflectance of only 0.7%. Microscopic analysis of cross-hatch areas on PMMA indicates superior adhesion and excellent environmental stability of ALD coatings. Furthermore, 3D conformal growth of ALD films is exploited on PMMA dome ensuring identical spectra on the entire dome surface.