Ultra-thin metallic films are widely applied in optics and microelectronics. However, their properties differ significantly from the bulk material and depend on the substrate material. The nucleation, film growth, and layer properties of atomic layer deposited (ALD) iridium thin films are evaluated on silicon wafers, BK7, fused silica, SiO2, TiO2, Ta2O5, Al2O3, HfO2, Ru, Cr, Mo, and graphite to understand the influence of various substrate materials. This comprehensive study was carried out using scanning electron and atomic force microscopy, X-ray reflectivity and diffraction, four-point probe resistivity and contact angle measurements, tape tests, and Auger electron spectroscopy. Within few ALD cycles, iridium islands occur on all substrates. Nevertheless, their size, shape, and distribution depend on the substrate. Ultra-thin (almost) closed Ir layers grow on a Ta2O5 seed layer after 100 cycles corresponding to about 5 nm film thickness. In contrast, the growth on Al2O3 and HfO2 is strongly inhibited. The iridium growth on silicon wafers is overall linear. On BK7, fused silica, SiO2, TiO2, Ta2O5, Ru, Cr, and graphite, three different growth regimes are distinguishable. The surface free energy of the substrates correlates with their iridium nucleation delay. Our work, therefore, demonstrates that substrates can significantly tailor the properties of ultra-thin films.

Scattering of ophthalmic devices is a complex phenomenon involving both surface and bulk light-material interactions. In this work, light scattering of nanocellulose reinforced PVA hydrogels contact lenses for ophthalmic applications was investigated. Optical microscopy, fluorescence microscopy and atomic force microscopy (AFM) techniques were used for ultrastructure characterization. Further, 3D angle resolved light scattering measurements in the visible spectral range were performed using a BTDF (bidirectional transmittance distribution function) sensor to quantify the scattered light. Surface and bulk scattering properties were discerned using white light interferometry. Total scatter levels ranging from 3% to 40% were observed depending on the hydrogel composition. The most critical factor affecting the light scattering properties in nanocellulose-reinforced PVA hydrogels was related to the state of hydration of the hydrogels, which is critical to maintain visual acuity of ophthalmic devices

Metallic coatings are essential for numerous optical systems due to their high and broadband reflectivity in the infrared spectral range. In contrast to well-established (protected) silver and gold mirror coatings, iridium is environmentally durable, referring to ISO 9211-3 and thermally stable up to 600 °C even without protective layers, as demonstrated. Additionally, the optical and related structural properties of atomic layer deposited (ALD) and magnetron sputtered (MS) Ir coatings were investigated using spectrophotometry, FTIR, ellipsometry, WLI, AFM, XRR, XRD, SEM, and electrical resistivity measurements. The properties of Ir ALD and Ir MS coatings differ due to their topography and microstructure.

We report for the first time the direct growth of molybdenum disulfide (MoS2) monolayers on nanostructured silicon-on-insulator waveguides. Our results indicate the possibility of utilizing the Chemical Vapour Deposition (CVD) on nanostructured photonic devices in a scalable process. Direct growth of 2D material on nanostructures rectifies many drawbacks of the transfer-based approaches. We show that the van der Waals material grow conformally across the curves, edges, and the silicon–SiO2 interface of the waveguide structure. Here, the waveguide structure used as a growth substrate is complex not just in terms of its geometry but also due to the two materials (Si and SiO2) involved. A transfer-free method like this yields a novel approach for functionalizing nanostructured, integrated optical architectures with an optically active direct semiconductor.

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