Optical Response of CVD-Grown ML-WS2 Flakes on an Ultra-Dense Au NP Plasmonic Array

Ferrera, Marzia; Ramó, Lorenzo; Convertino, Domenica; Orlandini, Giorgio; Milekhin, Ilya; Magnozzi, Michele; Rahaman, Mahfujur; Zahn, Dietrich R. T.; Coletti, Camilla; Canepa, M.; Bisio, Francesco

doi:10.3390/chemosensors10030120

Cited by 6 publications

(9 citation statements)

References 73 publications

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“…The investigated system is shown in the optical micrograph of figure 1(a). The CVD-grown WS 2 flake is characterized by a typical triangular shape and a monolayer thickness extending for hundreds of microns across [43,44,52]. At the center of the flake, a bilayer region with a 0 • twist angle is present (3R stacking).…”

Section: Resultsmentioning

confidence: 99%

“…In the present study, the local properties of WS 2 flakes encapsulated by hBN were analyzed. The flakes were grown on Si/SiO 2 substrate via liquid precursor chemical vapor deposition (LqP-CVD) in a two-zone horizontal furnace (Lenton) [43,44,[50][51][52]. The growth mechanism of the LqP-CVD process was reported in detail in [50], and here the main steps are summarized.…”

Section: Methodsmentioning

confidence: 99%

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Local dielectric function of hBN-encapsulated WS₂ flakes grown by chemical vapor deposition

Ferrera

Sharma²,

Milekhin³

et al. 2023

J. Phys.: Condens. Matter

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Hexagonal boron nitride (hBN), sometimes referred to as white graphene, receives growing interest in the scientific community, especially when combined into van der Waals homo- and heterostacks, in which novel and interesting phenomena may arise. hBN is also commonly used in combination with 2D semiconducting transition metal dichalcogenides (TMDCs). The realization of hBN-encapsulated TMDC homo- and heterostacks can indeed offer opportunities to investigate and compare TMDC excitonic properties in various stacking configurations. In this work, we investigate the optical response at the micrometric scale of mono- and homo-bilayer WS2 grown by chemical vapor deposition and encapsulated between two single layers of hBN. Imaging spectroscopic ellipsometry (ISE) is exploited to extract the local dielectric functions across one single WS2 flake and detect the evolution of excitonic spectral features from monolayer to bilayer regions. Exciton energies undergo a redshift by passing from hBN-encapsulated single layer to homo-bilayer WS2, as also confirmed by photoluminescence spectra. Our results can provide a reference for the study of the dielectric properties of more complex systems where hBN is combined with other 2D van der Waals materials into heterostructures and are stimulating towards the investigation of the optical response of other technologically-relevant heterostacks.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Local dielectric function of hBN-encapsulated WS₂ flakes grown by chemical vapor deposition

Ferrera

Sharma²,

Milekhin³

et al. 2023

J. Phys.: Condens. Matter

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“…Transmittance spectra are obtained by means of a homebuilt microspectroscopic setup. 60 For this experiment, two spectrometers are employed in tandem (AvaSpec-ULS2048XL-EVO and AvaSpec-NIR256-2.5-HSC-EVO from Avantes B. V., NS Apeldoorn, The Netherlands), covering a spectral range from 400 to 2240 nm with a measurement spot size of approximately 20 μm diameter.…”

Section: Methodsmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Thermal Scanning-Probe Lithography for Broad-Band On-Demand Plasmonic Nanostructures on Transparent Substrates

Ramò,

Giordano,

Ferrando

et al. 2023

ACS Appl. Nano Mater.

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Thermal scanning-probe lithography (t-SPL) is a high-resolution nanolithography technique that enables the nanopatterning of thermosensitive materials by means of a heated silicon tip. It does not require alignment markers and gives the possibility to assess the morphology of the sample in a noninvasive way before, during, and after the patterning. In order to exploit t-SPL at its peak performances, the writing process requires applying an electric bias between the scanning hot tip and the sample, thereby restricting its application to conductive, optically opaque, substrates. In this work, we show a t-SPL-based method, enabling the noninvasive high-resolution nanolithography of photonic nanostructures onto optically transparent substrates across a broad-band visible and near-infrared spectral range. This was possible by intercalating an ultrathin transparent conductive oxide film between the dielectric substrate and the sacrificial patterning layer. This way, nanolithography performances comparable with those typically observed on conventional semiconductor substrates are achieved without significant changes of the optical response of the final sample. We validated this innovative nanolithography approach by engineering periodic arrays of plasmonic nanoantennas and showing the capability to tune their plasmonic response over a broad-band visible and near-infrared spectral range. The optical properties of the obtained systems make them promising candidates for the fabrication of hybrid plasmonic metasurfaces supported onto fragile low-dimensional materials, thus enabling a variety of applications in nanophotonics, sensing, and thermoplasmonics.

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“…The unique capabilities of iSE make it a valuable tool for investigating 2D TMDCs and their properties. [51,52] Spatial maps of Ψ and Δ were acquired at six wavelengths within the relevant energy range, as described in the Experimental Section. The data was then converted into a thickness map using a layer-stack optical model comprising an optically semiinfinite Si substrate, a SiO 2 layer, and a MoS 2 layer.…”

Section: Imaging Spectroscopic Ellipsometrymentioning

confidence: 99%

Optimizing Gold‐Assisted Exfoliation of Layered Transition Metal Dichalcogenides with (3‐Aminopropyl)triethoxysilane (APTES): A Promising Approach for Large‐Area Monolayers

Petrini,

Peci,

Curreli

et al. 2024

Advanced Optical Materials

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Two‐dimensional transition metal dichalcogenides (2D TMDCs) have gained significant attention from the scientific community due to their exceptional properties. Recently, the metal‐assisted exfoliation technique has emerged as a promising method for producing large‐area, high‐quality 2D monolayers. However, achieving strong adhesion between metal foil and substrate during the exfoliation process remains a major challenge, preventing successful exfoliation. To overcome this issue, this study explores the application of (3‐Aminopropyl)triethoxysilane (APTES) as an adhesion layer to substantially improve adhesion between the monolayers and hydrophilic substrates such as SiO2, allowing for a high yield of mm‐sized monolayers. Two sample sets, obtained from the same MoS2 crystal via gold‐assisted exfoliation with APTES‐treated substrates and from standard scotch tape exfoliation, are statistically compared. APTES significantly improves exfoliation performance, yielding larger monolayers compared to conventional methods. This improvement enables the effective exfoliation with the gold‐tape method, which otherwise results in no yield. Through Raman and photoluminescence characterization techniques, it is found that the flakes obtained from gold‐assisted exfoliation and APTES are comparable to those obtained by standard scotch‐tape exfoliation in terms of defects and optical properties, showing signatures of strain‐induced Raman shift and n‐type doping.

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Optical Response of CVD-Grown ML-WS2 Flakes on an Ultra-Dense Au NP Plasmonic Array

Cited by 6 publications

References 73 publications

Local dielectric function of hBN-encapsulated WS₂ flakes grown by chemical vapor deposition

Local dielectric function of hBN-encapsulated WS₂ flakes grown by chemical vapor deposition

Thermal Scanning-Probe Lithography for Broad-Band On-Demand Plasmonic Nanostructures on Transparent Substrates

Optimizing Gold‐Assisted Exfoliation of Layered Transition Metal Dichalcogenides with (3‐Aminopropyl)triethoxysilane (APTES): A Promising Approach for Large‐Area Monolayers

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Optical Response of CVD-Grown ML-WS2 Flakes on an Ultra-Dense Au NP Plasmonic Array

Cited by 6 publications

References 73 publications

Local dielectric function of hBN-encapsulated WS2 flakes grown by chemical vapor deposition

Local dielectric function of hBN-encapsulated WS2 flakes grown by chemical vapor deposition

Thermal Scanning-Probe Lithography for Broad-Band On-Demand Plasmonic Nanostructures on Transparent Substrates

Optimizing Gold‐Assisted Exfoliation of Layered Transition Metal Dichalcogenides with (3‐Aminopropyl)triethoxysilane (APTES): A Promising Approach for Large‐Area Monolayers

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Local dielectric function of hBN-encapsulated WS₂ flakes grown by chemical vapor deposition

Local dielectric function of hBN-encapsulated WS₂ flakes grown by chemical vapor deposition