Abstract
Flat optics nanoarrays based on few-layer MoS2 are homogeneously fabricated over large-area (cm2) transparent templates, demonstrating effective tailoring of the photon absorption in two-dimensional (2D) transition-metal dichalcogenide (TMD) layers. The subwavelength subtractive re-shaping of the few-layer MoS2 film into a one-dimensional (1D) nanostripe array results in a pronounced photonic anomaly, tunable in a broadband spectral range by simply changing the illumination conditions (or the lattice periodicity). This scheme promotes efficient coupling of light to the 2D TMD layers via resonant interaction between the MoS2 excitons and the photonic lattice, with subsequent enhancement of absorption exceeding 400% relative to the flat layer. In parallel, an ultra-broadband absorption amplification in the whole visible spectrum is achieved, thanks to the non-resonant excitation of substrate guided modes promoted by MoS2 nanoarrays. These results highlight the potential of nanoscale re-shaped 2D TMD layers for large-area photon harvesting in layered nanophotonics, quantum technologies and new-generation photovoltaics.
Highlights
The controlled reshaping of few-layer 2D MoS2 films grown by physical vapour deposition (PVD) over a large area[46] has been achieved by means of an original variant of laser interference lithography (LIL) described in the Methods section and in Fig. S1 and Table S1 in the Electronic supplementary information (ESI).† This cost-effective nanofabrication approach enables us to manufacture highly ordered MoS2 gratings with controlled periodicity that are highly stable in time and extend homogenously on flat and transparent silica substrates, giving an opportunity to tailor optical properties in the 2D layer
The capability to reshape the 2D MoS2 layers forming highly ordered anisotropic lattices is clearly shown by the scanning electron microscopy (SEM) images in Fig. 1a and b, where the electronic contrast highlights the laterally disconnected polycrystalline MoS2 nanostripes with respect to the dielectric substrate
The nanostripes extend uninterrupted over macroscopic areas, enabling the excitation and detection via standard far-field optical spectroscopy of coherent optical modes induced by the gratings
Summary
Due to the inherent low photon absorption in 2D atomic layers, novel photon harvesting strategies need to be developed in order to effectively couple light with the active 2D material. One possibility in this respect is given by flat-optics metasurfaces based on subwavelength lattices which are capable of tailoring light matter interaction at the nanoscale via light scattering and/or near-field confinement,[27,28,29,30,31,32,33] so as to amplify the overall optical absorption in the 2D active layer. Lattice resonances or Rayleigh Anomalies (RA) in photonic arrays represent an effective light-trapping strategy, inducing strong in-plane light deflection and confinement.[34,35,36,37,38] This light trapping approach has been widely reported in the case of noble metal or dielectric nanostructures, but a strong potential is expected in the case of 2D TMDs, such as MoS2, provided light trapping and enhanced photo-conversion and/or -detection functionalities can be obtained by direct patterning of the atomically thin material.[39,40]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
