Visibly transparent amorphous silicon for functional dielectric metasurfaces

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Enhanced cross-polarization efficiency of a-Si:H metasurfaces via chemical equilibrium in PE-CVD

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Tailored refractive index of hydrogenated amorphous silicon for dielectric metasurface

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Suppressing optical losses of hydrogenated amorphous silicon for fucntional photonic platforms working at the visible spectrum

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Revealing Structural Disorder in Hydrogenated Amorphous Silicon for a Low-Loss Photonic Platform at Visible Frequencies

The high refractive index of hydrogenated amorphous silicon (a-Si:H) at optical frequencies is an essential property for the efficient modulation of the phase and amplitude of light. However, substantial optical loss represented by its high extinction coefficient prevents it from being utilized widely. Here, the bonding configurations of a-Si:H are investigated, in order to manipulate the extinction coefficient and produce a material that is competitive with conventional transparent materials, such as titanium dioxide and gallium nitride. This is achieved by controlling the hydrogenation and silicon disorder by adjusting the chemical deposition conditions. The extinction coefficient of the low-loss a-Si:H reaches a minimum of 0.082 at the wavelength of 450 nm, which is lower than that of crystalline silicon (0.13). Beam-steering metasurfaces are demonstrated to validate the low-loss optical properties, reaching measured efficiencies of 42%, 62%, and 75% at the wavelengths of 450, 532, and 635 nm, respectively. Considering its compatibility with mature complementary metal-oxide-semiconductor processes, the low-loss a-Si:H will provide a platform for efficient photonic operating in the full visible regime.11Nsciescopu

Increased electrical conductivity of peptides through annealing process

Biocompatible biologically occurring polymer is suggested as a component of human implantable devices since conventional inorganic materials are apt to trigger inflammation and toxicity problem within human body. Peptides consisting of aromatic amino acid, tyrosine, are chosen, and enhancement on electrical conductivity is studied. Annealing process gives rise to the decrease on resistivity of the peptide films and the growth of the carrier concentration is a plausible reason for such a decrease on resistivity. The annealed peptides are further applied to an active layer of field effect transistor, in which low on/off current ratio (∼10) is obtained

Tyrosine-mediated analog resistive switching for artificial neural networks

The fourth industrial revolution indispensably brings explosive data processing and storage; thus, a new computing paradigm based on artificial intelligence-enabling device structure is urgently required. Memristors have received considerable attention in this regard because of their ability to process and store data at the same location. However, fundamental problems with abrupt switching characteristics limit their practical application. To address this problem, we utilized the concept of metaplasticity inspired by biosystems and observed gradual switching in the peptide-based memristor at high proton conductivity. An unexpectedly high slope value > 1.7 in the log/-V curve at low voltage (<= 400 mV) was considered the main origin, and it might arise from the modulatory response of proton ions on the threshold of Ag ion migration in the peptide film. With the obtained gradual switching property at high proton conductivity, the device showed significantly increased accuracy of image recognition (similar to 82.5%). We believe that such a demonstration not only contributes to the practical application of neuromorphic devices but also expands the bioinspired functional synthetic platform.N

Magnetic Control of the Plasmonic Chirality in Gold Helicoids

Chiral plasmonic nanostructures have facilitated a promising method for manipulating the polarization state of light. While a precise structural modification at the nanometer-scale-level could offer chiroptic responses at various wavelength ranges, a system that allows fast response control of a given structure has been required. In this study, we constructed uniformly arranged chiral gold helicoids with cobalt thin-film deposition that exhibited a strong chiroptic response with magnetic controllability. Tunable circular dichroism (CD) values from 0.9° to 1.5° at 550 nm wavelength were achieved by reversing the magnetic field direction. In addition, a magnetic circular dichroism (MCD) study revealed that the gap structure and size-related surface plasmon resonance induced MCD peaks. We demonstrated the transmitted color modulation, where the color dynamically changed from green-to-red, by controlling the field strength and polarizer axis. We believe current work broadens our understanding of magnetoplasmonic nanostructure and expands its potential applicability in optoelectronics or optical-communications

Circularly polarized light-sensitive, hot electron transistor with chiral plasmonic nanoparticles

© 2022. The Author(s).The quantitative detection of circularly polarized light (CPL) is necessary in next-generation optical communication carrying high-density information and in phase-controlled displays exhibiting volumetric imaging. In the current technology, multiple pixels of different wavelengths and polarizers are required, inevitably resulting in high loss and low detection efficiency. Here, we demonstrate a highly efficient CPL-detecting transistor composed of chiral plasmonic nanoparticles with a high Khun's dissymmetry (g-factor) of 0.2 and a high mobility conducting oxide of InGaZnO. The device successfully distinguished the circular polarization state and displayed an unprecedented photoresponsivity of over 1 A/W under visible CPL excitation. This observation is mainly attributed to the hot electron generation in chiral plasmonic nanoparticles and to the effective collection of hot electrons in the oxide semiconducting transistor. Such characteristics further contribute to opto-neuromorphic operation and the artificial nervous system based on the device successfully performs image classification work. We anticipate that our strategy will aid in the rational design and fabrication of a high-performance CPL detector and opto-neuromorphic operation with a chiral plasmonic structure depending on the wavelength and circular polarization state.Y