The escalating demand for wearable electronics has become a driving force behind the surge in research on energy storage systems capable of powering these novel devices. The increased desire for flexible and elastic electronic devices has amplified demand to overcome the challenges associated with developing highperformance electrical energy sources that maintain electrochemical and mechanical stability under significant strain deformation. In this study, we present a novel approach to fabricate highly flexible supercapacitors composed of single-walled carbon nanotubes (SWCNT) and manganese dioxide (MnO2), showcasing an impressive areal capacitance of 249 mF/cm2. The even distribution of MnO2 within the SWCNT matrix results in supercapacitors with exceptional electrochemical and mechanical properties. Notably, these supercapacitors can undergo a 400% stretch while retaining 95% of their original capacitance. Moreover, they exhibit stability during electrochemical and mechanical cycling, maintaining 88% capacitance after 10,000 charging cycles and 85% after 4000 mechanical stretching cycles.

This paper demonstrates a significant advance in creating ultra-flat Si(100) surfaces suitable for low thermal budget device fabrication. This is achieved by a two-step pre-flash and protect (PFP) process that locks in an atomically flat surface that survives subsequent device processing steps. The first PFP step is a high-temperature flash in ultra-high vacuum (UHV) that creates an atomically flat surface. The second PFP step is a Piranha solution treatment that preserves the surface with a thin oxide shortly after removal from UHV. This oxide can then be easily removed with buffered oxide etchant (BOE) as needed during subsequent device fabrication. Following BOE, a surface with angstrom-level flatness is recovered, obviating the need for more aggressive thermal or chemical surface flattening processes. With this new process no aggressive chemical cleaning, such as RCA cleaning, is needed and no high-temperature surface cleaning or flattening is required for nanoscale device fabrication. This method offers promising opportunities for device fabrication and other applications that require clean and atomically flat Si(100) surfaces and low thermal budget device processing.

Fabricating organic semiconducting materials into large-scale, well-organized architectures is critical for building high-performance molecular electronics. While graphene nanoribbons (GNRs) hold enormous promise for various device applications, their assembly into a well-structured monolayer or multilayer architecture poses a substantial challenge. Here, we report the preparation of length-defined monodisperse GNRs via the integrated iterative binomial synthesis (IIBS) strategy and their self-assembly into submicrometer architectures with long-range order, uniform orientation, as well as regular layers. The use of short alkyl side chains benefits forming stable multilayers through interlocking structures. By changing the length and backbone shapes of these monodisperse GNRs, various three-dimensional assemblies, including multilayer stripes, monolayer stripes, and nanowires, can be achieved, leading to different photophysical properties and band gaps. The discovery of these intriguing self-assembly behaviors of length-defined GNRs is expected to enable various future applications.

Bottom-up synthesis of graphene nanoribbons (GNRs) from aryl halide precursors is often performed thermally or in-solution, without detailing the local molecular assembly or the precursor's response to electromechanics perturbation. This synthetic approach forms nanoribbons with well-defined widths and atomically precise edges, which are necessary for ensuring bandgap uniformity. However, neither on-surface nor solution-based GNR synthesis techniques adequately address the problem of positional control, which is crucial to the fabrication of GNR transistors. To better understand this issue, we investigate the on-surface ordering of 10, 10'-dibromo-9, 9'-bianthracene (DBBA), the 7A-GNR monomer precursor. Scanning tunneling microscopy imaging shows that DBBA molecules spontaneously assemble on Au(111) into non-covalent two-dimensional islands. By varying sample temperature during and after deposition, we observe three different adsorbate arrangements. These two-dimensional packing structures demonstrate differing responses to localized excitations. The difference in packing structures and their respective responses to electro-mechanical perturbations can give us insight into how to best optimize conditions for locally controlled and large-scale thermal GNR polymer growth.

Spin states in semiconductors provide exceptionally stable and noise-resistant environments for qubits, positioning them as optimal candidates for reliable quantum computing technologies. The proposal to use nuclear and electronic spins of donor atoms in silicon, introduced by Kane in 1998, sparked a new research field focused on the precise positioning of individual impurity atoms for quantum devices, utilising scanning tunnelling microscopy and ion implantation. This roadmap article reviews the advancements in the 25 years since Kane’s proposal, the current challenges, and the future directions in atomic-scale semiconductor device fabrication and measurement. It covers the quest to create a silicon-based quantum computer and expands to include diverse material systems and fabrication techniques, highlighting the potential for a broad range of semiconductor quantum technological applications. Key developments include phosphorus in silicon devices such as single-atom transistors, arrayed few-donor devices, one- and two-qubit gates, three-dimensional architectures, and the development of a toolbox for future quantum integrated circuits. The roadmap also explores new impurity species like arsenic and antimony for enhanced scalability and higher-dimensional spin systems, new chemistry for dopant precursors and lithographic resists, and the potential for germanium-based devices. Emerging methods, such as photon-based lithography and electron beam manipulation, are discussed for their disruptive potential. This roadmap charts the path toward scalable quantum computing and advanced semiconductor quantum technologies, emphasising the critical intersections of experiment, technological development, and theory.

Scalable fabrication of graphene nanoribbons with narrow band gaps has been a nontrivial challenge. Here, we have developed a simple approach to access narrow band gaps using hybrid edge structures. Bottom-up liquid-phase synthesis of bent N = 6/8 armchair graphene nanoribbons (AGNRs) has been achieved in high efficiency through copolymerization between an o-terphenyl monomer and a naphthalene-based monomer, followed by Scholl oxidation. An unexpected 1,2-aryl migration has been discovered, which is responsible for introducing kinked structures into the GNR backbones. The N = 6/8 AGNRs have been fully characterized to support the proposed structure and show a narrow band gap and a relatively high electrical conductivity. In addition, their application in efficient gas sensing has also been demonstrated.

This paper demonstrates the fabrication of nanometer-scalemetalcontacts on individual graphene nanoribbons (GNRs) and the use ofthese contacts to control the electronic character of the GNRs. Wedemonstrate the use of a low-voltage direct-write STM-based processto pattern sub-5 nm metallic hafnium diboride (HfB2) contactsdirectly on top of single GNRs in an ultrahigh-vacuum scanning tunnelingmicroscope (UHV-STM), with all the fabrication performed on a technologicallyrelevant semiconductor silicon substrate. Scanning tunneling spectroscopy(STS) data not only verify the expected metallic and semiconductingcharacter of the contacts and GNR, respectively, but also show inducedband bending and p-n junction formation in the GNR due to themetal-GNR work function difference. Contact engineering withdifferent work function metals obviates the need to create GNRs withdifferent characteristics by complex chemical doping. This is a demonstrationof the successful fabrication of precise metal contacts and localp-n junction formation on single GNRs.

AbstractUltrathin, lightweight, and flexible aligned single-walled carbon nanotube (SWCNT) films are fabricated by a facile, environmentally friendly, and scalable printing methodology. The aligned pattern and outstanding intrinsic properties render “metal-like” thermal conductivity of the SWCNT films, as well as excellent mechanical strength, flexibility, and hydrophobicity. Further, the aligned cellular microstructure promotes the electromagnetic interference (EMI) shielding ability of the SWCNTs, leading to excellent shielding effectiveness (SE) of ~ 39 to 90 dB despite a density of only ~ 0.6 g cm−3 at thicknesses of merely 1.5–24 µm, respectively. An ultrahigh thickness-specific SE of 25 693 dB mm−1 and an unprecedented normalized specific SE of 428 222 dB cm2 g−1 are accomplished by the freestanding SWCNT films, significantly surpassing previously reported shielding materials. In addition to an EMI SE greater than 54 dB in an ultra-broadband frequency range of around 400 GHz, the films demonstrate excellent EMI shielding stability and reliability when subjected to mechanical deformation, chemical (acid/alkali/organic solvent) corrosion, and high-/low-temperature environments. The novel printed SWCNT films offer significant potential for practical applications in the aerospace, defense, precision components, and smart wearable electronics industries.

Submitted for the MAR07 Meeting of The American Physical Society Synthesis of Narrow Chirality Distributions of Single-Walled Carbon Nanotubes using Catalyst Particle Templates Produced by Nanosphere Lithography NOUREDDINE TAYEBI, JOSEPH LYDING, University of Illinois at Urbana-Champaign — We report a simple and inexpensive technique based on nanosphere lithography [1], which allows for the fabrication of periodically-spaced and monodispersed metal particles from which the chemicalvapor-deposition synthesis of single-walled carbon nanotubes (SWNTs) is achieved. We have controlled the diameter of these metal particles, and thus that of the SWNTs, from 1 nm down to 0.7 nm, with an interparticle spacing varying from 50 nm down to 5 nm. Raman spectroscopy analysis reveals that a narrow chirality distribution is achieved. We are currently confirming the chirality results using fluorescence spectroscopy and scanning tunneling microscopy. Transmission electron microscopy analysis reveals that the 0.7 nm particles are crystallographically identical, which could be the origin of such a narrow distribution. Furthermore, the current technique was used to grow aligned SWNTs on single-crystal quartz substrates [2]. [1] J. C. Hulteen et al., J Vac Sci Technol A, 13, 1553 (1995) [2] C. Kocabas et al., J Am Chem Soc, 128, 4540 (2006) Noureddine Tayebi University of Illinois at Urbana-Champaign Date submitted: 20 Nov 2006 Electronic form version 1.4

The goal of this project was to develop a high-speed, high-temperature motor capable of operating at 650 ºC, 60,000 rpm, and 125 kW with 50 kW/L. Key objectives to achieve this goal were to develop a suitable high-temperature wire, designing and fabricating rotor and stator subassemblies, designing an inverter assembly, and thermomechanical validation of the fully assembled motor. Four candidates for high-temperature wire were evaluated using test solenoid structures and finite element analysis modeling. The best candidate was a silicone-enameled copper wire suitable for continuous operation at 593 ºC. The rotor for the motor was designed to use a composite material comprised of 74% iron and 26% mullite by volume. This material would be suitable for 3D printing of the rotor. At the end of the project a vacuum mixer was under construction to produce the bubble-free material needed to achieve the highest strength composite after 3D printing. Rotor testing at 60,000 rpm would have commenced immediately following the additive manufacturing process. The project abruptly ended when key personnel left the project without notice.

Graphene nanoribbons (GNRs) attract a growing interest due to their tunable physical properties and promise for device applications. A variety of atomically precise GNRs have recently been synthesized by on-surface and solution approaches. While on-surface GNRs can be conveniently visualized by scanning tunneling microscopy (STM), and their electronic structure can be probed by scanning tunneling spectroscopy (STS), such characterization remains a great challenge for the solution-synthesized GNRs. Here, we report solution synthesis and detailed STM/STS characterization of atomically precise GNRs with a meandering shape that are structurally related to chevron GNRs but have a reduced energy band gap. The ribbons were synthesized by Ni0-mediated Yamamoto polymerization of specially designed molecular precursors using triflates as the leaving groups and oxidative cyclodehydrogenation of the resulting polymers using Scholl reaction. The ribbons were deposited onto III-V semiconducting InAs(110) substrates by a dry contact transfer technique. High-resolution STM/STS characterization not only confirmed the GNR geometry, but also revealed details of electronic structure including energy states, electronic band gap, as well as the spatial distribution of the local density of states. The experimental STS band gap of GNRs is about 2 eV, which is very close to 2.35 eV predicted by the density functional theory simulations with GW correction, indicating a weak screening effect of InAs(110) substrate. Furthermore, several aspects of GNR-InAs(110) substrate interactions were also probed and analyzed, including GNR tunable transparency, alignment to the substrate, and manipulations of GNR position by the STM tip. The weak interaction between the GNRs and the InAs(110) surface makes InAs(110) an ideal substrate for investigating the intrinsic properties of GNRs. Because of the reduced energy band gap of these ribbons, the GNR thin films exhibit appreciably high electrical conductivity and on/off ratios of about 10 in field-effect transistor measurements, suggesting their promise for device applications.

The electrical conductivity and mechanical strength of fibers constructed from single-walled carbon nanotubes (CNTs) are usually limited by the weak interactions between individual CNTs. In this work, we report a significant enhancement of both of these properties through chemical cross-linking of individual CNTs. The CNT fibers are made by wet-spinning a CNT solution that contains 1,3,5-tris(2'-bromophenyl)benzene (2TBB) molecules as the cross-linking agent, and the cross-linking is subsequently driven by Joule heating. Cross-linking with 2TBB increases the conductivity of the CNT fibers by a factor of ∼100 and increases the tensile strength on average by 47%; in contrast, the tensile strength of CNT fibers fabricated without 2TBB decreases after the same Joule heating process. Symmetrical supercapacitors made from the 2TBB-treated CNT fibers exhibit a remarkably high volumetric energy density of ∼4.5 mWh cm-3 and a power density of ∼1.3 W cm-3.

Periodic surface structures at the nanometer or micrometer scale have been achieved by various methods, while atomic-scale surface structures over large areas are unavailable. Herein, we report the formation of highly coherent atomic-scale ripple patterns on bulk metallic glass (MG) surfaces by low-energy ion irradiation. The pattern arises through three consecutive stages: emergence of initial random dots, subsequent transition to ripples, and ordering of the ripple pattern through annihilation reactions of mobile defects, while the wavelength and amplitude remain invariant throughout the patterning. No pattern is generated for the crystalline counterpart at the same irradiation condition. These observations suggest a distinct ripple forming process typical of MGs associated with their enhanced surface mobility, which enables a controllable self-organization approach for large-area surface structuring with atomic-scale precision.

The lack of surface states within the band gap of the perfect Si(100)2x1:H surface opens the way to scanning tunneling microscopy studies of dopant atom sites in Si(100). In this paper, Boron and Arsenic induced features are studied by ultrahigh vacuum scanning tunneling microscopy. The values of their amplitudes naturally group such that several subsurface layers can be identified. This technique for producing atom-resolved three-dimensional maps of electrically active dopants in silicon may be a useful metric for characterizing dopant profiles in ultra-small electronic device structures.

2D Quantum Metamaterials, pp. 23-32 (2019) No Access3: Definition of atomically precise fabrication and quantum metamaterialsNeil Curson, Joseph Lyding, Richard Silver, Scott Schmucker, and John N. RandallNeil CursonUniversity College London, UK, Joseph LydingUniversity of Illinois at Urbana-Champaign, USA, Richard SilverNational Institute of Standards and Technology, USA, Scott SchmuckerNational Institute of Standards and Technology, USA, and John N. RandallZyvex Labs, USAhttps://doi.org/10.1142/9789811206061_0003Cited by:0 PreviousNext AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsRecommend to Library ShareShare onFacebookTwitterLinked InRedditEmail Abstract: The following sections are included: Fabrication challenges to overcome — precision, scale Advantages and disadvantages from a state-of-the-art perspective Prospects for nanomanufacturing and the scale up problem FiguresReferencesRelatedDetails 2D Quantum MetamaterialsMetrics History PDF download

Silica-based glass is a household name, providing insulation for windows to microelectronics. The debate over the types of motions thought to occur in or on SiO2 glass well below the glass transition temperature continues. Here, we form glassy silica films by oxidizing the Si(100) surface (from 0.5 to 1.5 nm thick, to allow tunneling). We then employ scanning tunneling microscopy in situ to image and classify these motions at room temperature on a millisecond to hour time scale and 50-pm to 5-nm length scale. We observe two phenomena on different time scales. Within minutes, compact clusters with an average diameter of several SiO2 glass-forming units (GFUs) hop between a few (mostly two) configurations, hop cooperatively (facilitation), and merge into larger clusters (aging) or split into smaller clusters (rejuvenation). Within seconds, Si-O-Si bridges connect two GFUs within a single cluster flip, providing a vibrational fine structure to the energy landscape. We assign the vibrational fine structure using electronic structure calculations. Calculations also show that our measured barrier height for whole cluster hopping at the glass surface (configurational dynamics) is consistent with the configurational entropy predicted by thermodynamic models of the glass transition and that the vibrational entropy for GFU flipping and configurational entropy for cluster hopping are comparable (on a per GFU basis).