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- 2018
- computer statistical experiment
- statistical optimization
- resonant-tunneling diode
- negative voltage current differential resistance
- characteristics
- heterojunction
- quantum well
- resonant tunneling border
- Electronic Science and Technology
- Optoelectronic Information Science and Engineering
- Bauman Moscow State Technical University
- V.N. Karazin Kharkiv National University
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Control of electromagnetically induced grating by surface plasmon and tunneling in a hybrid QD-MNP system
摘要： We investigate the electromagnetically induced grating (EIG) in a quantum dot-metal nanoparticle (QD-MNP) hybrid system. The EIG can be controlled and improved by the surface plasmon effect and the interdot tunneling effect between quantum dots. By manipulating the tunneling effect and the QD-MNP distance, not only the first-order diffraction intensity of the grating can be efficiently enhanced, but also the EIG can be switched from the absorption grating to the gain grating. Almost two times of the first-order diffraction efficiencies can be achieved in the gain gratings compared with the absorption gratings.
关键词： electromagnetically induced grating,dot-metal nanoparticle,electromagnetically induced transparency,plasmon-exciton effect,tunneling
更新于2025-09-04 15:30:14
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Formation mechanism of twin domain boundary in 2D materials: The case for WTe2
摘要： Our scanning tunneling microscopy (STM) study observes, for the first time, twin domain boundary (TDB) formations on the surface of WTe2 single crystal, which is glued by solidifying indium to Si substrate. In these TDB regions, a large inhomogeneous strain field, especially a critical shear strain of about 7%, is observed by geometric phase analysis. This observation does not obey the old believe that a small mechanical stress is sufficient to drive thermally-induced TDB formations in two-dimensional materials. To resolve the contradiction, we perform density functional theory calculations combined with elasticity theory analysis, which show that TDBs on WTe2 are entirely displacement-induced, for which a critical strain is necessary to overcome the onset barrier.
关键词： WTe2,twin domain boundary,density functional theory,strain,scanning tunneling microscopy (STM)
更新于2025-09-04 15:30:14
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Scanning frequency comb microscopy—A new method in scanning probe microscopy
摘要： A method for superimposing a microwave frequency comb (MFC) on the DC tunneling current in a scanning tunneling microscope (STM) is described in which a mode-locked laser is focused on the tunneling junction. The MFC is caused by optical rectification of the regular sequence of laser pulses due to the nonlinear current-voltage characteristics of the tunneling junction. Hundreds of harmonics, at integer multiples of the laser pulse-repetition frequency, are generated with a metal tip and sample. However, the harmonics have less power with a resistive sample due to the loss in its spreading resistance. The microwave power is greatest at a tip-sample distance that is unique for each sample resistivity. This distance may be set by using different pairs of the applied DC bias and the set-point for the DC tunneling current. However, the laser, and not the applied DC bias or the DC tunneling current, is the source of energy for the MFC so they are not required. Feedback control of the tip-sample distance may be based on maximizing the attowatt-level microwave power of the harmonics, which have a signal-to-noise ratio of 20 dB. This method shows promise for nondestructive carrier profiling of semiconductors with true sub-nanometer resolution which is essential in the continued progress below the 40-nm technology node. It may enable carrier profiling with 2-D materials such as graphene, and it also shows promise for finer resolution in images of biological materials or other resistive samples.
关键词： optical rectification,microwave frequency comb,resistive sample,feedback control,scanning tunneling microscope
更新于2025-09-04 15:30:14
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Designing multidirectional energy splitters and topological valley supernetworks
摘要： Using group theoretic and topological concepts, together with tunneling phenomena, we geometrically design interfacial wave networks that contain splitters which partition energy in two, three, four, or five directions. This enriches the valleytronics literature that has, so far, been limited to two-directional splitters. Additionally, we describe a design paradigm that gives greater detail about the relative transmission along outgoing leads, away from a junction; previously, only the negligible transmission leads were predictable. We utilize semianalytic numerical simulations, as opposed to finite element methods, to clearly illustrate all of these features with highly resolved edge states. As a consequence of this theory, networks, with directionality tunable by geometry, ideal for applications such as beam-splitters, switches, and filters are created. Coupling these networks that contain multidirectional energy-splitters culminates in the realization of a topological supernetwork.
关键词： multidirectional energy splitters,valleytronics,topological valley supernetworks,group theoretic,tunneling phenomena,topological concepts
更新于2025-09-04 15:30:14
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[IEEE 2018 International Russian Automation Conference (RusAutoCon) - Sochi (2018.9.9-2018.9.16)] 2018 International Russian Automation Conference (RusAutoCon) - Application of Computer Statistical Experiment for Studying Resonant-Tunneling Diode Parameter Reproducibility Under Batch Production Conditions
摘要： The object of research is a resonant-tunneling diode (RTD) based on GaAs/AlGaAs multilayer heterostuctures. A software package based on the resonant-tunneling diode current-voltage characteristic’s high-speed modeling algorithm with a computer statistical experiment module is submitted. The developed package was used for studying the diode’s design parameters’ technological errors’ effect on the RTD I-V characteristics’ variation. The results' adequacy is verified by comparison with the experimental data.
关键词： computer statistical experiment,statistical optimization,resonant-tunneling diode
更新于2025-09-04 15:30:14
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Performance of resonant tunneling diodes based on the nonpolar-oriented AlGaN/GaN heterostructures
摘要： The performance of resonant tunneling diodes (RTDs) based on nonpolar-oriented AlGaN/GaN heterostructures has been theoretically investigated by numerical simulation. Simulation results show that the RTDs grown along the nonpolar orientation can yield the current–voltage (I–V ) characteristics with the peak current, the peak-to-valley ratio (PVCR), and the peak voltage of about 3.5 times and 1.5 times higher and 1.1 times lower than those of RTDs grown along the conventional polar orientation, respectively. The results also show excellent symmetry, high reproducibility of I–V characteristics, and high intrinsic response frequency.
关键词： current–voltage characteristics,resonant tunneling diodes,numerical simulation,AlGaN/GaN heterostructures,nonpolar orientation
更新于2025-09-04 15:30:14
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BODIPY with Tuned Amphiphilicity as Fluorogenic Plasma Membrane Probe
摘要： Staining of the plasma membrane (PM) is essential in bio-imaging as it delimits the cell surface and provides various information regarding the cell morphology and status. Herein, the lipophilicity of a green-emitting BODIPY fluorophore was tuned by gradual functionalization with anchors composed of zwitterionic and aliphatic groups, thus yielding three different amphiphilic dyes. We found that BODIPY bearing one or three anchors failed in efficiently staining the PM: derivative with one anchor showed low affinity to PM and exhibited strong fluorescence in water due to high solubility, whereas BODIPY with three anchors aggregated strongly in media and precipitated before binding to PM. In sharp contrast, the BODIPY bearing two anchors (B-2AZ, MemBright-488) formed virtually non-fluorescent soluble aggregates in aqueous medium that quickly de-aggregated in the presence of PM leading to bright soluble molecular form (quantum yield of 0.92). This fluorogenic response allowed for efficient probing of the PM at low concentration (20 nM) with high signal to background ratio images in mono- as well as two-photon excitation microscopy. B-2AZ proved to selectively stain the PM in a more homogeneous manner than the commercially available fluorescently labelled lectin WGA. Finally, it was successfully used in 3D-imaging to reveal fine intercellular tunneling nanotubes in KB cells and to stain the PM in glioblastoma cells in spheroids.
关键词： tunneling nanotubes,two-photon imaging,spheroids,Plasma membrane probe,fluorogenic probe
更新于2025-09-04 15:30:14
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Force-noise spectroscopy by tunneling current deflection sensing
摘要： An electro-mechanical setup for the measurement of force-noise properties in a low-temperature tunneling microscope has been utilized to enable extremely high resolution and acquire force-noise spectra as function of the applied voltage bias. The direct crosstalk of vibrations onto the tunneling current is used to measure the de?ection of a force-sensing cantilever. We demonstrate its capability to measure the mechanical energy of the cantilever, caused by the noise of the force from vacuum tunneling between polycrystalline Iridium electrodes. We observe peak levels of the induced cantilever energy at polarity-symmetric voltages corresponding to dominant peaks of the phonon density of states, which suggests that inelastic transport processes contribute to force ?uctuations.
关键词： inelastic transport processes,force-noise spectroscopy,cantilever deflection,tunneling current,phonon density of states
更新于2025-09-04 15:30:14