Graphene nanoribbons (GNRs) have promising applications in future nanoelectronics, chemical sensing and electrical interconnects. Although there are quite a few GNR nanofabrication methods reported, a rapid and low-cost fabrication method that is capable of fabricating arbitrary shapes of GNRs with good-quality is still in demand for using GNRs for device applications. In this paper, we present a tip-based nanofabrication method capable of fabricating arbitrary shapes of GNRs. A heated atomic force microscope (AFM) tip deposits polymer nanowires atop a CVD-grown graphene surface. The polymer nanowires serve as an etch mask to define GNRs through one step of oxygen plasma etching similar to a photoresist in conventional photolithography. Various shapes of GNRs with either linear or curvilinear features are demonstrated. The width of the GNR is around 270 nm and is determined by the width of the depositing polymer nanowire, which we estimate can be scaled down 15 nms. We characterize our TBN-fabricated GNRs using Raman spectroscopy and I-V measurements. The measured sheet resistances of our GNRs fall within the range of 1.65 kΩ/□ - 2.64 kΩ/□, in agreement with previously reported values. Furthermore, we determined the high-field breakdown current density of GNRs to be approximately 2.94×10 A/cm. This TBN process is seamlessly compatible with existing nanofabrication processes, and is particularly suitable for fabricating GNR based electronic devices including next generation DNA sequencing technologies and beyond silicon field effect transistors.
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http://dx.doi.org/10.1039/C5RA04257G | DOI Listing |
J Chem Phys
December 2024
Department of Chemistry, Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, USA.
A simplified theoretical description of multiple-quantum excitation and mixing for nuclear magnetic resonance of half-integer quadrupolar nuclei is presented. The approach recasts the multiple-quantum nutation behavior in terms of reduced excitation and mixing curves through a scaling of the first-order offset frequency by the quadrupolar coupling constant. The two-dimensional correlation of the static first-order anisotropic line shape to the second-order anisotropic magic-angle-spinning (MAS) line shape is utilized to transform the three-dimensional integral over the three Euler angles into a single integral over the dimensionless first-order offset parameter.
View Article and Find Full Text PDFAdv Mater
December 2024
Advanced Microscopy and Instrumentation Research Center, Harbin Institute of Technology, Harbin, 150080, P. R. China.
Nowadays, metasurfaces have attracted considerable attention due to their promising and advanced control of electromagnetic (EM) waves. However, it is still challenging to shape guided waves into desired free-space mode, while simultaneously manipulating spatial incident waves using a single metasurface. Herein, a class of metasurfaces capable of multiplexing guided and space waves is proposed to achieve advanced EM functionalities in microwave regions, which can find great application potentials in radar systems, wireless communications, and wireless power transfer (WPT).
View Article and Find Full Text PDFEur J Obstet Gynecol Reprod Biol
December 2024
Division of Gynecology and Obstetrics, Department of Surgical Sciences, University of Cagliari, Cagliari, Italy.
Background: Subtle uterine lesions are abnormal intracavitary conditions that, while not causing significant anatomical changes, can adversely impact fertility. Identifying these "subtle" lesions is challenging due to arbitrary interpretation, varied management strategies, unclear clinical significance, and insufficient clinician training in recognizing them. Hysteroscopy offers direct visualization and the capacity to obtain targeted biopsies, making it an invaluable tool for the diagnosis and treatment of these often overlooked conditions.
View Article and Find Full Text PDFAnal Chem
December 2024
Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
Ultramicro pipettes with circular orifices have practically become common probes in exploring the microscopic world, yet the versatility of differently shaped pipettes is undermined in the pore family. Herein, ultramicro triangular pipettes with a pseudotriangular-shaped orifice were fabricated by laser-pulling triangular quartz capillaries and characterized by microscopic and electrochemical methods. Then, the differences in the electrochemical behaviors of triangular and circular pores were revealed through experiments and simulations.
View Article and Find Full Text PDFPhys Rev E
November 2024
Department of Physics, PUC-Rio, Rua Marquês de São Vicente 225, 22451-900, Rio de Janeiro, RJ, Brazil.
We investigate random searches under stochastic position resetting at rate r, in a bounded 1D environment with space-dependent diffusivity D(x). For arbitrary shapes of D(x) and prescriptions of the associated multiplicative stochastic process, we obtain analytical expressions for the average time T for reaching the target (mean first-passage time), given the initial and reset positions, in good agreement with stochastic simulations. For arbitrary D(x), we obtain an exact closed-form expression for T, within a Stratonovich scenario, while for other prescriptions, like Itô and anti-Itô, we derive asymptotic approximations for small and large rates r.
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