Ms. Mehrnaz Modaresialam Profile

Mehrnaz Modaresialam

at IM2NP

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Publications (3)

Proceedings Article | 1 August 2021 Presentation

Scalable disordered hyperuniform architectures via nano-imprint lithography of metal oxides for different photonic applications

Zeinab Chehadi, Mohammed Bouabdellaoui, Mehrnaz Modaresialam, David Grosso, Marco Abbarchi

Proceedings Volume 11802, 118020A (2021) https://doi.org/10.1117/12.2595567

KEYWORDS: Oxides, Metals, Lithography, Sol-gels, Silica, Solid state physics, Silicon, Polymers, Photonic devices, Glasses

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Proceedings Article | 18 April 2021 Presentation

Dielectric nano-imprint lithography-sol-gel nanostructured for high-sensitivity refractive index sensing

Mehrnaz Modaresialam, Luc Favre, Zeinab Chehadi, Marco Abbarchi, David Grosso

Proceedings Volume 11772, 1177216 (2021) https://doi.org/10.1117/12.2593440

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Proceedings Article | 18 April 2021 Presentation + Paper

Methylated silica surfaces having tapered nipple-dimple nano-pillar morphologies as robust broad-angle and broadband anti-reﬂection coatings

Mehrnaz Modaresialam, Jean-Benoît Claude, David Grosso, Marco Abbarchi

Proceedings Volume 11769, 117690Z (2021) https://doi.org/10.1117/12.2593454

KEYWORDS: Silica, Refractive index, Glasses, Polymers, Nanostructures, Nanoimprint lithography, Solar cells, Semiconducting wafers, Resistance, Nanolithography

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In this work, mechanically, chemically, and thermally resistant broadband and broad-angle antireﬂection coatings were prepared on 10 cm diameter glass substrates combining sol−gel deposition with nanoimprint lithography. The coatings are composed of water-repellent methylated silica (Si₄O₇Me₂) and exhibit a transverse refractive index gradient created by tapered, nipple-dimple, subwavelength nanostructures, featuring a record vertical aspect ratio of ∼1.7. The structure is composed of hexagonal arrays of nanopillars (∼200 nm height, ∼120 nm width) and holes (∼50 nm depth, ∼100 nm width) with a 270 nm pitch. The corresponding eﬀective refractive index is between 1.2 and 1.26, depending on the fabrication conditions. Total transmission for double-face nanoimprint wafers reaches 96−97% in the visible range; it is limited by specular reﬂection and mostly by the intrinsic diﬀusion of the glass substrate. The antireﬂective eﬀect is eﬀective up to an ∼60° incidence angle. We address the robustness of the inorganic-based coating in various realistic and extreme conditions, comparing them to the organic perﬂuoropolyether (PFPE) counterpart (master reference). The sol−gel system is extremely stable at high temperature (up to 600 °C, against 200 °C for the polymer reference). Both systems showed excellent chemical stability, except in strong alkaline conditions. The inorganic nanostructure showed an abrasion resistance of more than 2 orders of magnitude superior to the polymer one with less than 20% loss of antireﬂective performance after 2000 rubbing cycles under an ∼2 N cm⁻² pressure. This diﬀerence springs from the large elastic modulus of the sol−gel material combined with an excellent adhesion to the substrate and to the speciﬁc nipple-dimple conformation. The presence of holes allows maintaining a refractive index gradient proﬁle even after tearing out part of the nanopillar population. Our results are relevant to applications where transparent windows with broadband and broad-angle transmission are needed, such as protective glasses on photovoltaic cells or C-MOS cameras.

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