For THz rectennas, ultra-fast diodes are required. While the metal-insulator-metal (MIM) diode has been investigated in recent years, it suffers from large resistance and capacitance, as well as a low cut-off frequency. Alternatively, a geometric diode can be used, which is more suitable due to its planar structure. However, there is only one report of a THz geometric diode based on a monolayer graphene. It is based on exfoliated graphene, and thus, it is not suitable for mass production. In this work, we demonstrate chemical vapor deposition (CVD)-grown monolayer graphene based geometric diodes, which are mass-producible. The diode's performance has been studied experimentally by varying the neck widths from 250-50 nm, the latter being the smallest reported neck width for a graphene geometric diode. It was observed that by decreasing the neck widths, the diode parameters such as asymmetry, nonlinearity, zero-bias resistance, and responsivity increased within the range studied. For the 50 nm neck width diode, the asymmetry ratio was 1.40 for an applied voltage ranging from -2 V to 2 V, and the zero-bias responsivity was 0.0628 A/W. The performance of the diode was also verified through particle-in-cell Monte Carlo simulations, which showed that the simulated current-voltage characteristics were consistent with our experimental results.
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http://dx.doi.org/10.3390/nano11081986 | DOI Listing |
ACS Appl Electron Mater
January 2025
Electrical Engineering Division, Engineering Department, University of Cambridge, Cambridge CB3 0FA, U.K.
Nanoscale semiconductors offer significant advantages over their bulk semiconductor equivalents for electronic devices as a result of the ability to geometrically tune electronic properties, the absence of internal grain boundaries, and the very low absolute number of defects that are present in such small volumes of material. However, these advantages can only be realized if reliable contacts can be made to the nanoscale semiconductor using a scalable, low-cost process. Although there are many low-cost "bottom-up" techniques for directly growing nanomaterials, the fabrication of contacts at the nanoscale usually requires expensive and slow techniques like e-beam lithography that are also hard to scale to a level of throughput that is required for commercialization.
View Article and Find Full Text PDFJ Phys Chem A
January 2025
Shandong Province Key Laboratory of Medical Physics and Image Processing Technology, School of Physics and Electronics, Shandong Normal University, Jinan 250014, China.
Organic room-temperature phosphorescence (RTP) emitters with long lifetimes, high exciton utilizations, and tunable emission properties show promising applications in organic light-emitting diodes (OLEDs) and biomedical fields. Their excited-state properties are highly related to single molecular structure, aggregation morphology, and external stimulus (such as hydrostatic pressure effect). To gain a deeper understanding and effectively regulate the key factors of luminescent efficiency and lifetime for RTP emitters, we employ the thermal vibration correlation function (TVCF) theory coupled with quantum mechanics/molecular mechanics (QM/MM) calculations to investigate the photophysical properties of three reported RTP crystals (Bp-OEt, Xan-OEt, and Xan-OMe) with elastic/plastic deformation.
View Article and Find Full Text PDFSpectrochim Acta A Mol Biomol Spectrosc
December 2024
School of Chemistry and Environmental Engineering, Changchun University of Science and Technology, Jilin Provincial Science and Technology Innovation Center of Optical Materials and Chemistry, Jilin Provincial International Joint Research Center of Photo-functional Materials and Chemistry, Changchun 130022, China; State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun 130021, China. Electronic address:
Neutral radicals have the potential to construct pure organic light-emitting diodes (OLEDs) with internal quantum efficiencies reaching 100%. However, neutral radical luminescent materials with emission wavelengths in the second near-infrared (NIR-II) window are rare. Herein, a serial of neutral donor-bridge-acceptor (D-π-A) type radical derivatives are investigated.
View Article and Find Full Text PDFACS Nano
December 2024
School of Engineering Science, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada.
Sci Adv
December 2024
Huanjiang Laboratory, Department of Engineering Mechanics, Soft Matter Research Center, Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province, State Key Laboratory of Brain-Machine Intelligence, Zhejiang University, Zhejiang, China.
Transfer printing based on tunable and reversible adhesive that enables the heterogeneous integration of materials is essential for developing envisioned electronic systems. An adhesive with both adhesion enhancement and reduction capabilities in a rapid and selective manner is challenging. Here, we report a laser-induced adhesive, featuring a geometrically simple shape memory polymer layer on a glass backing, with excellent adhesion modulation capability for programmable pickup and noncontact printing of microchips.
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