A repository & source of cutting edge news about emerging terahertz technology, it's commercialization & innovations in THz devices, quality & process control, medical diagnostics, security, astronomy, communications, applications in graphene, metamaterials, CMOS, compressive sensing, 3d printing, and the Internet of Nanothings. NOTHING POSTED IS INVESTMENT ADVICE! REPOSTED COPYRIGHT IS FOR EDUCATIONAL USE.
Showing posts with label Maruthi Nagavalli Yogeesh. Show all posts
Showing posts with label Maruthi Nagavalli Yogeesh. Show all posts
Patterning graphene into nanoribbons (graphene nanoribbons, GNR) allows for tunability in the emerging fields of plasmonic devices in the mid-infrared and terahertz regime. However, the fabrication processes of GNR arrays for plasmonic devices often include a low-throughput electron beam lithography step that cannot be easily scaled to large areas. In this study, we developed a GNR fabrication method using block copolymer (BCP) lithography that takes advantage of the wetting transparency of graphene. One major advantage of this method is that the self-assembled domains of the polystyrene-block-poly(methyl methacrylate) BCP are oriented perpendicularly directly on top of the graphene where they can later serve as an etch mask. Large area (cm2 scale, 3 μm × 3 μm defect-free area) 13–51 nm wide GNR arrays were successfully fabricated using this scalable protocol. This wetting transparency-assisted GNR fabrication method could be useful for high-throughput production of various plasmonic devices, including biosensors, and photodetectors.
Patterned arrays of graphene nanostructures, also referred as graphene metasurfaces, have proven to be capable of efficiently coupling with incident light by surface plasmon resonances. In this work, a new type of graphene metasurfaces with moiré patterns using cost-effective and scalable moiré nanosphere lithography (MNSL) is demonstrated. A large gradient in feature size (i.e., from sub-200 nm to 1.1 μm) of the graphene nanostructures exists in single metasurfaces. The in-plane quasi-periodic arrangement of the graphene nanostructures can be easily tuned to form a variety of moiré patterns. The experimental measurement and numerical simulations show that the graphene moiré metasurfaces support tunable and multiband optical responses due the size and shape dependences of surface plasmon resonance modes of graphene nanostructures. It is also demonstrated that the multiband optical responses of graphene moiré metasurfaces can be tuned from mid-infrared (MIR) to terahertz (THz) regimes by choosing polystyrene spheres of different sizes for MNSL. These findings provide a cost-effective and scalable strategy to achieve ultrathin functional devices, including multiband light modulators, broadband biosensors, and multiband photodetectors, which feature tunable and multiband responses in wide range of wavelengths from MIR to THz.
