Self-assembled antireflection coatings for light trapping based on SiGe random metasurfaces

Bouabdellaoui, Mohammed; Checcucci, Simona; Wood, Thomas; Naffouti, Meher; Sena, Robert Paria; Liu, Kailang; Ruiz, Carmen M.; Duché, David; Rouzo, Judikaël Le; Escoubas, Ludovic; Berginc, Gérard; Bonod, Nicolas; Zazoui, M.; Favre, Luc; Leo, Metayer
,; Ronda, A.; Berbézier, Isabelle; Grosso, David; Gurioli, Massimo; Abbarchi, Marco

doi:10.1103/physrevmaterials.2.035203

Cited by 15 publications

(23 citation statements)

References 73 publications

(125 reference statements)

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“…All these spectra are normalized to the scattering from a Lanbertian reference after subtracting the background. The spectrum of particles on the BOX does not show any resonance and is rather smooth with larger intensity at shorter wavelength, whereas for the transferred ones it features pronounced modulations, as expected for dielectric Mie resonators accounting for the presence of multi-polar resonances ( figure 5) [27,30,33,34,[36][37][38]. Very similar results were obtained for other samples with SiGe and Ge particles transferred in PDMS (not shown).…”

Section: Methods B: Transfer In Pdms Slicessupporting

confidence: 80%

“…By monitoring the light diffusion we observe the presence of size-dependent resonances with a peak at about 900nm for the larger particles obtained from 30nm a-Ge dewetting, and at 700nm for the smaller ones from 10nm a-Ge ( figure 4(b), top and bottom panels respectively). These bands are interpreted as multi-polar Mie modes sustained by the particles, as expected for this kind of devices [27,30,33,34,[36][37][38].…”

Section: Methods A: Transfer Of Spontaneously Dewetted Islands From 50supporting

confidence: 62%

“…This process results in a bi-modal size distribution of large, Si-rich islands (base size from 250 up to 500 nm) and small, Ge-rich islands (base size from 200 up to 300 nm). In contrast with the previous case, large and small islands can be perfectly mixed together by adding Ge during the annealing step (figure 1(c), fifth panel) [33].…”

Section: Panorama Of Different Dewetting Scenariosmentioning

confidence: 65%

“…We showcased method A on 50mm wafer, that represents a record for solid state dewetting of group IV materials [33] as well as for bendable dielectric metasurfaces based on Mie resonators (previous reports [24] were implemented on a few mm 2 ). The merit of our demonstration is also to extend these kind of techniques to SiGe alloys and pure Ge, that are relevant emerging materials for applications in photonics [33,34] including the important case of integration on plastic supports [40].…”

Section: Discussionmentioning

confidence: 99%

“…Method B is based on PDMS (figure 2, bottom panels): it is implemented by directly pouring the mixed PDMS reactants (90% RTV141A and 10% RTV141B from BLUESIL) onto the samples (after HF attack), [27] first topped with Si 1−x Ge x alloys and then annealed to produce large SiGe-based islands (third panel), first partially dewetted and than topped with Ge to form bimodal distribution of spatially-separate Si rich and Ge-rich islands (fourth panel) [28], or annealed during Ge deposition to produce bimodal spatially-mixed large and small islands [33]. pumping under primary vacuum and finally cross-linking at 70°C in an oven (from Binder) for 30 min under room atmosphere.…”

Section: Nano-transfer On Transparent Substratesmentioning

confidence: 99%

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Flexible photonic devices based on dielectric antennas

et al. 2020

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Flexible and stretchable photonics are emerging fields aiming to develop novel applications where the devices need to conform to uneven surfaces or whenever lightness and reduced thickness are major requirements. However, owing to the relatively small refractive index of transparent soft matter including most polymers, these materials are not well adapted for light management at visible and near-infrared frequencies.Here we demonstrate simple, low cost and efficient protocols for fabricating Si 1−x Ge x -based, sub-micrometric dielectric antennas over record scales (50 mm wafers) with ensuing hybrid integration into different plastic supports. The transfer process has a near-unity yield: up to 99.94% for disordered structures and 99.5% for the ordered counterpart. Finally, we benchmark the optical quality of the dielectric antennas with light scattering measurements, demonstrating the control of the islands structural color and the onset of sharp Mie modes after encapsulation in plastic. Thanks to the ease of implementation of our fabrication methods, these results are relevant for the integration of SiGe-based dielectric Mie resonators in flexible substrates over large surfaces.

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Section: Methods B: Transfer In Pdms Slicessupporting

confidence: 80%

Section: Methods A: Transfer Of Spontaneously Dewetted Islands From 50supporting

confidence: 62%

Section: Panorama Of Different Dewetting Scenariosmentioning

confidence: 65%

Section: Discussionmentioning

confidence: 99%

Section: Nano-transfer On Transparent Substratesmentioning

confidence: 99%

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Flexible photonic devices based on dielectric antennas

et al. 2020

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Titania‐Based Spherical Mie Resonators Elaborated by High‐Throughput Aerosol Spray: Single Object Investigation

Checcucci

Bottein

Claude

et al. 2018

Adv Funct Materials

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The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10. 1002/adfm.201801958. tives to replace complex and bulky optical elements. This unique ability is due to strong modifications of the local density of optical states occurring in sub-micrometric objects made of materials featuring high dielectric constant and sufficiently small absorption losses.Most studies over the last years have mainly addressed silicon- [4][5][6][7][8][9][10] and germanium-based [11][12][13][14] Mie resonators, demonstrating that they could outperform their metallic counterpart supporting localized plasmonic resonances. However, the large absorption of group IV semiconductor compounds at short wavelengths induces strong optical losses, limiting their potential applicability as efficient devices especially at blue and near-UV frequencies [15,16] (e.g. at 450 nm: n Si = 4.5, k Si = 0.13; n Ge = 4.0, k Ge = 2.24). Furthermore, with a few exception based on colloids [4,17,18] and solid state dewetting, [13,[19][20][21][22][23] typical nanofabrication methods of Si(Ge)-based Mie resonators rely on top-down technologies that are not easy to scale-up at affordable prices.TiO 2 -based optical devices are an interesting alternative to Si, since Titania has a relatively high refractive index and is fully transparent up to UV frequencies [24,25] (e.g.: at 450 nm: n TiO2 = 2.55, k TiO2 = 1.2 × 10 −5 ; at 370 nm: n TiO2 = 2.83, k TiO2 = 1 × 10 −3 ) rendering it, for instance, a strategic material to manipulate the light emitted by conventional GaN-based blue LEDs (at about 450 nm). TiO 2 can be prepared by high-throughput chemical processes, which is a prerequisite for applications requiring large surface systems. It also has many other advantages over Si and metals that are its high chemical, mechanical, and thermal stability, nontoxicity, and relative natural abundance.To date, several groups have studied the properties of Titania particles as dielectric resonators prepared using conventional top-down microfabrication technologies [26][27][28][29][30] or soft-nanoimprint lithography. [31,32] They all confirmed that electromagnetic resonances could be generated within these metal oxide objects. However, the limited exploitation of this material is mainly due to the difficulty in applying conventional top-down fabrication methods to TiO 2 . Additionally, such approaches do not allow the preparation of spherical resonators, [33] which may be interesting for many applications with effective metamaterials, such as beam steering and back-scattering-free optics, [11,[34][35][36][37][38][39][40][41][42][43][44][45]

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Multifunctional Metasurfaces Based on Direct Nanoimprint of Titania Sol–Gel Coatings

Checcucci

Bottein

Gurioli

et al. 2019

Advanced Optical Materials

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shaping, [12][13][14] sensing, [15,16] and nonlinear phenomena [17][18][19][20] are few examples demonstrating the strength of this approach for light management with sub-wavelength dielectric structures. However, with a few exceptions based on colloidal assembly, [21][22][23] hydrothermal growth, [20] solid state dewetting, [24][25][26][27][28][29][30] and aerosol spray, [31] most of these achievements were based on complex and expensive fabrication methods involving several steps (such as e-beam lithography and reactive ion etching). Top-down fabrication approaches limit the full exploitation of Mie resonators for unexpensive devices and broad areas production. In particular, given the rapidly rising interest in structural coloring and light filtering with dielectric metasurfaces [32][33][34][35][36][37][38][39][40][41] a versatile and scalable method is highly desirable to overcome the gap separating mere proof of principles and industrial applications. In this framework, a major step forward would be the development of fabrication techniques fully compatible with back-end processing of C-MOS circuitry (e.g., keeping the maximal processing temperature below ≈450 °C) or more generally, on electronic devices such as LEDs and photovoltaic panels.So far, most studies on Mie resonators are based on Si or Ge materials, due to both their very large index of refraction and the possibility to exploit the well-developed nanofabrication approaches of nanoelectronics and nanophotonics. Among other materials, TiO 2 (titania) is recently attracting growing interest [35,[42][43][44][45][46] for its transparency up to near-UV frequencies and its relatively high refractive index. Indeed, TiO 2 -based Mie resonators systems can potentially outperform conventional Si and Ge-based dielectric metasurfaces, which suffer from larger absorption at short wavelength [47,48] (e.g., at 450 nm: n TiO2 = 2.55, k TiO2 = 1.2 × 10 −5 ; n Si = 4.5; k Si = 0.13; n Ge = 4; and k Ge = 2.24). A quite unique peculiarity of titania is the tunable porosity (adjustable by modifying the sol-gel fabrication process) and therefore permeability to liquids and gas. In addition to this, titania is an abundant, cheap, nontoxic, photocatalytic, mechanically strong, and chemically stable material, featuring a relatively low mass density (≈3.8 g cm −3 in the anatase form against ≈5 g cm −3 for MoS 2 ). These features make titania an ideal metamaterial providing several functions (e.g., tunable structural color, sensing small changes in the environment), for a novel photonic platform in view of multifunctional devices. Dielectric Mie resonators are taking momentum in the last years thanks to their peculiar properties in light management at visible and near-infrared frequencies. However, their full exploitation demands for cheap materials and versatile fabrication methods, extendible over large surfaces and potentially C-MOS compatible. Here, a sol-gel deposition and nanoimprint lithography method is used to obtain titania-based Mie resonators over large areas (s...

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Self-assembled antireflection coatings for light trapping based on SiGe random metasurfaces

Cited by 15 publications

References 73 publications

Flexible photonic devices based on dielectric antennas

Flexible photonic devices based on dielectric antennas

Titania‐Based Spherical Mie Resonators Elaborated by High‐Throughput Aerosol Spray: Single Object Investigation

Multifunctional Metasurfaces Based on Direct Nanoimprint of Titania Sol–Gel Coatings

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