Infrared absorption spectroscopy of vibro-rotational molecular resonances provides a powerful method for investigation of a wide range of molecules and molecular compounds. However, the wavelength of light required to excite these resonances is often orders of magnitude larger than the absorption cross sections of the molecules under investigation. This mismatch makes infrared detection and identification of nanoscale volumes of material challenging. Here we demonstrate a new type of infrared plasmonic antenna for long-wavelength nanoscale enhanced sensing. The plasmonic materials utilized are epitaxially grown semiconductor engineered metals, which results in high-quality, low-loss infrared plasmonic metals with tunable optical properties. Nanoantennas are fabricated using nanosphere lithography, allowing for cost-effective and large-area fabrication of nanoscale structures. Antenna arrays are optically characterized as a function of both the antenna geometry and the optical properties of the plasmonic semiconductor metals. Thin, weakly absorbing polymer layers are deposited upon the antenna arrays, and we are able to observe very weak molecular absorption signatures when these signatures are in spectral proximity to the antenna resonance. Experimental results are supported with finite element modeling with strong agreement.
One-dimensional crystal growth allows the epitaxial integration of compound semiconductors on silicon (Si), as the large lattice-mismatch strain arising from heterointerfaces can be laterally relieved. Here, we report the direct heteroepitaxial growth of a mixed anion ternary InAsyP1-y nanowire array across an entire 2 in. Si wafer with unprecedented spatial, structural, and special uniformity across the entire 2 in. wafer and dramatic improvements in aspect ratio (>100) and area density (>5 × 10(8)/cm(2)). Heterojunction solar cells consisting of n-type InAsyP1-y (y = 0.75) and p-type Si achieve a conversion efficiency of 3.6% under air mass 1.5 illumination. This work demonstrates the potential for large-scale production of these nanowires for heterogeneous integration of optoelectronic devices.
Producing densely packed high aspect ratio InGaAs nanostructures without surface damage is critical for beyond Si-CMOS nanoelectronic and optoelectronic devices. However, conventional dry etching methods are known to produce irreversible damage to III-V compound semiconductors because of the inherent high-energy ion-driven process. In this work, we demonstrate the realization of ordered, uniform, array-based InGaAs pillars with diameters as small as 200 nm using the damage-free metal-assisted chemical etching (MacEtch) technology combined with the post-MacEtch digital etching smoothing. The etching mechanism of InGaAs is explored through the characterization of pillar morphology and porosity as a function of etching condition and indium composition. The etching behavior of InGaAs, in contrast to higher bandgap semiconductors (e.g., Si or GaAs), can be interpreted by a Schottky barrier height model that dictates the etching mechanism constantly in the mass transport limited regime because of the low barrier height. A broader impact of this work relates to the complete elimination of surface roughness or porosity related defects, which can be prevalent byproducts of MacEtch, by post-MacEtch digital etching. Side-by-side comparison of the midgap interface state density and flat-band capacitance hysteresis of both the unprocessed planar and MacEtched pillar InGaAs metal-oxide-semiconductor capacitors further confirms that the surface of the resultant pillars is as smooth and defect-free as before etching. MacEtch combined with digital etching offers a simple, room-temperature, and low-cost method for the formation of high-quality InGaAs nanostructures that will potentially enable large-volume production of InGaAs-based devices including three-dimensional transistors and high-efficiency infrared photodetectors.
Cellular microstructures form naturally in many living organisms (e.g., flowers and leaves) to provide vital functions in synthesis, transport of nutrients, and regulation of growth. Although heterogeneous cellular microstructures are believed to play pivotal roles in their three-dimensional (3D) shape formation, programming 3D curved mesosurfaces with cellular designs remains elusive in man-made systems. We report a rational microlattice design that allows transformation of 2D films into programmable 3D curved mesosurfaces through mechanically guided assembly. Analytical modeling and a machine learning–based computational approach serve as the basis for shape programming and determine the heterogeneous 2D microlattice patterns required for target 3D curved surfaces. About 30 geometries are presented, including both regular and biological mesosurfaces. Demonstrations include a conformable cardiac electronic device, a stingray-like dual mode actuator, and a 3D electronic cell scaffold.
Articles you may be interested inInvestigation of high hole mobility In0.41Ga0.59Sb/Al0.91Ga0.09Sb quantum well structures grown by molecular beam epitaxy Appl. Phys. Lett. 104, 052111 (2014); 10.1063/1.4865091 Molecular beam epitaxy growth of high electron mobility InAs/AlSb deep quantum well structure Direct growth of hexagonal InN films on 6H-SiC by radio-frequency metal-organic molecular-beam epitaxya)The authors demonstrate the ability of high-quality epitaxial InAs films to be used as wavelengthflexible, low-loss, engineered plasmonic metals across the mid-infrared spectral range. Films are grown by molecular beam epitaxy and characterized by Hall effect measurements, atomic force microscopy, and infrared reflection and transmission spectroscopy. The losses of our plasmonic material are studied as a function of InAs doping density, growth rate, buffer layer type, and substrate type. High growth rates are shown to be integral to obtaining films with low losses and doping densities approaching 1Â10 20 cm À3 .
2000759 (6 of 38) www.advmattechnol.de Figure 4. Flexible microwave transistors. a) Schematic illustration of fabrication process flow of flexible microwave TFTs based on Si nanomembrane. Left, two-step transfer-printing of Si nanomembrane on flexible substrate with assist of PDMS stamp. Right, direct flip-printing Si nanomembrane on flexible substrate. Reproduced with permission. [72] Copyright 2010, Wiley-VCH. b) Flexible microwave Si TFT using direct flip-printing approach in (a). Reproduced under the terms of the Creative Commons Attribution 4.0 International License. [75] Copyright 2016, Springer Nature. c) Flexible microwave Si TFT using two-step approach in (a). Reproduced with permission. [72] Copyright 2010, Wiley-VCH. d) Cross-section SEM image of flexible Si MOSFET made by thinning a 65 nm node SOI wafer. Reproduced with permission. [45] Copyright 2013, American Institute of Physics. e) Optical images of flexible GaAs HBT on cellulose nanofibril (CNF) substrate. Reproduced under the terms of the Creative Commons Attribution 4.0 International License. [90] Copyright 2015, Springer Nature. f) Schematic illustration and normalized on-state conductance (G/G 0), maximum transconductance (g m /g m0) of flexible InAs MOSFET with self-aligned gate. Reproduced with permission. [53] Copyright 2012, American Chemical Society. g) Cross-section schematic illustration and gain curves of flexible InGaAs/InAlAs HEMT as function of frequency under various bending conditions. Reproduced with permission. [91] Copyright 2013, American Institute of Physics. h) Output power density (P OUT), power gain (G P) and power-added efficiency (PAE) of the flexible GaN HEMT on thermal conductive tape with thermal conductivity of 1.6 W m −1 K −1. Reproduced with permission. [92] Copyright 2017, Wiley-VCH. i) Photography of AlGaN/GaN film grown on BN coated sapphire substrate and printed on flexible tape. Reproduced with permission. [19] Copyright 2017, Wiley-VCH. j) Cross-section schematic illustration of bottom gate flexible graphene FET (GFET). Reproduced with permission. [93] Copyright 2013, American Chemical Society. k) Cross-section schematic illustration of top gate flexible GFET with self-aligned gate configuration. Reproduced with permission. [94] Copyright 2014, American Chemical Society. l) High-frequency characteristics of flexible GFET with gate length of 50 nm. Reproduced with permission. [95] Copyright 2018, Wiley-VCH. m) Schematic illustration and gain curves of flexible microwave transistor based on MoS 2 as function of frequency. Reproduced with permission. [96] Copyright 2014, Springer Nature. n) High-frequency characteristics of flexible microwave transistor based on black phosphorus (BP) as function of frequency. Reproduced with permission.
Versatile wood cellulose, the most prototypical abundant polymer on earth, is considered a promising natural material for the fabrication of biodegradable electronics. The development of biodegradable electronics may help alleviate the adverse environmental impact caused by the fast‐growing electronic waste (e‐waste). The focus of this review is to discuss recent major advances in biodegradable electronics with versatile wood cellulose in terms of supporting substrates and functional components. First, the biological biodegradation and structural hierarchy of versatile wood cellulose is briefly introduced, followed by highlighting three types of cellulose substrates (opaque and hazy cellulose paper, transparent and clear cellulose film, and transparent and hazy cellulose film) for biodegradable electronics. Then, recent progress and research achievements in the use of versatile wood cellulose with multiscale dimensions in biodegradable electronics as a functional component (e.g., advanced light management layer, high capacitance dielectric, and ionic conductor) or even smart materials (e.g., mechanochromic layer, humidity sensing layer, adaptable adhesive layer, and piezoelectric component) are summarized in detail. Finally, an overview of challenges and perspectives for biodegradable electronics with versatile cellulose is provided.
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