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Tuning Spontaneous Emission through Waveguide Cavity Effects in Semiconductor Nanowires
摘要： The ability to tailor waveguide cavities and couple them with quantum emitters has developed a realm of nano-photonics encompassing, for example, highly efficient single photon generation or the control of giant photon nonlinearities. Opening new grounds by pushing the interaction of the waveguide cavity and integrated emitters further into the deep subwavelength regime, however, has been complicated by nonradiative losses due to the increasing importance of surface defects when decreasing cavity dimensions. Here, we show efficient suppression of nonradiative recombination for thin waveguide cavities using core?shell semiconductor nanowires. We experimentally reveal the advantages of such nanowires, which host mobile emitters, that is, free excitons, in a one-dimensional (1D) waveguide, highlighting the resulting potential for tunable, active, nanophotonic devices. In our experiment, controlling the nanowire waveguide diameter tunes the luminescence lifetime of excitons in the nanowires across 2 orders of magnitude up to 80 ns. At the smallest wire diameters, we show that this luminescence lifetime can be manipulated by engineering the dielectric environment of the nanowires. Exploiting this unique handle on the spontaneous emission of mobile emitters, we demonstrate an all-dielectric spatial control of the mobile emitters along the axis of the 1D nanowire waveguide.
关键词： Semiconductor nanowire,free excitons,photonic waveguide cavity,subwavelength nanophotonics,luminescence lifetime,tunable spontaneous emission
更新于2025-09-11 14:15:04
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Terahertz Transition-Edge Sensor with Kinetic-Inductance Amplifier at 4.2 K
摘要： Different terrestrial terahertz applications would benefit from large-format arrays, operating in compact and inexpensive cryocoolers at liquid helium temperature with sensitivity, limited only by the 300-K background radiation. A voltage-biased Transition-Edge Sensor (TES) as a THz detector can have sufficient sensitivity and has a number of advantages important for real applications: linearity of response, high dynamic range and a simple calibration. However it requires a low-noise current readout. Usually, a current amplifier based on Superconducting Quantum-Interference Device (SQUID) is used for readout, but the scalability of this approach is limited due to complexity of the operation and fabrication. Recently, it has been shown that instead of SQUID it is possible to use a current sensor, which is based on the nonlinearity of the kinetic inductance of a current-carrying superconducting stripe. Embedding the stripe into a microwave high-Q superconducting resonator allows for reaching sufficient current sensitivity. More important, it is possible with the resonator approach to scale up to large arrays using Frequency-Division Multiplexing (FDM) in GHz range. Here, we demonstrate the operation of a voltage-biased TES with a microwave kinetic-inductance current amplifier at 4.2 K. We measured the expected intrinsic Noise-Equivalent Power NEP ~ 5×10-14 W/Hz1/2 and confirmed that a sufficient sensitivity of the readout can be reached in conjunction with a real TES operation. The construction of an array with the improved sensitivity ~ 10-15 W/Hz1/2 at 4.2 K could be realized using a combination of the new current amplifier and already existing TES detectors with improved thermal isolation.
关键词： Transition-Edge Sensor,Superconducting nanowire,High-Q resonator,Nonlinear kinetic inductance,Terahertz arrays
更新于2025-09-11 14:15:04
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Analysis on DC and AC Characteristics of Self Heating Effect in Nanowire
摘要： As devices are scaling down aggressively, three-dimensional field-effect transistors (FETs) becomes one of essential factors to obtain high gate controllability in order to reduce leakage current. However, insulators surrounding channel for above the reason block heat emission so that the lattice temperature can increase to the critical levels for devices. This phenomenon, called Self Heating Effect (SHE), can deteriorate device performance significantly. From this point of view, overall study on SHE in 5 nm node Nanowire FET (NWFET) was implemented by simulation. Through analysis on on-current (Ion), thermal resistance (Rth), transient characteristics, the DC and AC characteristics were investigated.
关键词： Thermal Resistance (Rth),Self Heating Effect (SHE),Nanowire FET (NWFET)
更新于2025-09-11 14:15:04
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[IEEE 2018 XXIIIrd International Seminar/Workshop on Direct and Inverse Problems of Electromagnetic and Acoustic Wave Theory (DIPED) - Tbilisi, Georgia (2018.9.24-2018.9.27)] 2018 XXIIIrd International Seminar/Workshop on Direct and Inverse Problems of Electromagnetic and Acoustic Wave Theory (DIPED) - Optical Diffraction Radiation of a Beam of Particles Flowing Near a Circular Silver Nanowire
摘要： The optical diffraction radiation that accompanies the motion of a modulated beam of electrons near a silver nanowire scatterer is investigated in the two-dimensional formulation. Our goal is to compute the field in the near and far zones and analyze how it depends on electron beam parameters. We demonstrate the excitation of plasmon resonances of such a nanoscale scatterer that can be used in the design of optical range non-invasive beam position monitors.
关键词： plasmon resonance,diffraction radiation,surface wave,total scattering cross-section,nanowire scatterers,absorption cross-section
更新于2025-09-10 09:29:36
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Enhanced flow boiling in silicon nanowire-coated manifold microchannels
摘要： An experimental study was carried out to investigate the heat transfer, pressure drop and flow instability characteristics associated with the flow pattern of deionized water during two-phase boiling in a silicon-based manifold microchannel heat sink coated with silicon nanowires (SiNWs) compared to a plain-wall device. The manifold microchannel device featured parallel transverse microchannels etched on a silicon substrate and longitudinal microchannels etched on a glass cover plate. Silicon nanowires were generated on the bottom and the sidewalls of the silicon microchannels. A closed-loop experimental system was constructed to demonstrate thermal and hydraulic performance. Experimental results were presented with mass fluxes ranging from 250 to 1250 kg/m2s and subcooled inlet temperatures from 15 K to 65 K. Results for the SiNWs device showed an approximate 20% improvement in heat flux rejection compared to the plain-wall device under the same wall superheat conditions. A subcooled inlet temperature of 65 K associated with a mass flux of 1250 kg/m2s is shown to be capable of dissipating an effective heat flux of 431.3 W/cm2 with a wall superheat of about 85K. Overall, the SiNW coatings proved positive effects on enhancing the flow boiling heat transfer with slower pressure drop increase, meanwhile the three-dimensional manifold microchannel design is revealed to effectively mitigate flow instability during the entire single and two-phase flow regions. This indicates great potential in utilizing three-dimensional flows by integrating SiNWs surface structures in high heat flux cooling applications.
关键词： silicon nanowire,manifold microchannel,flow boiling,two-phase
更新于2025-09-10 09:29:36
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VHF-PECVD FABRICATION PARAMETERS DEPENDENT MORPHOLOGYVARIATION OF GOLD CATALYST ASSISTED SILICON THIN FILM GROWTH
摘要： Achieving two dimensional quantum structure of silicon with well-defined tunable morphology is an outstanding issue. We present the preliminary results on fabrication parameters dependent silicon thin film production using VHF-PECVD method. Five samples are prepared on Si(100) substrate with gold (Au) catalyst by adjusting different parameters such as deposition time, temperature and the flow of precursor gas. The samples morphology are analyzed using FESEM. The results reveal that the silicon thin film appear to be smooth and more uniform after an enormous amount of hydrogen is inserted together with the precursor gas (silane) during the deposition process. More interestingly, the films exhibit silicon nanowires as the deposition time is increased up to 1 hour. This morphological transformation is attributed to the vapor-liquid-solid (VLS) mechanism related to the deposition process.
关键词： VHF-PECVD,FESEM,nanowire,VLS
更新于2025-09-10 09:29:36
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[Nanostructure Science and Technology] Nanowire Electronics || Nanowire Bioelectronics
摘要： A bioelectronic device transduces a biological signal to or from an electrical signal at the bioelectronic interface. For example, an affinity biosensor employs a surface-immobilized recognition probe such as enzyme, antibody, or single-stranded nucleic acid to selectively capture a target analyte from solution. This biological recognition process is then converted into a measurable electrical signal in the biosensor, which allows for quantitative analysis of the target. Another example of bioelectronics is to record or stimulate bioelectrical activity from an electrogenic cell, such as neuron or cardiomyocyte. The translation between the ionic and electronic signals is enabled through either electrochemical reactions at the surface of a metal electrode or capacitive coupling at the interface between a transistor and a cell. Advanced electrophysiological tools are being developed to reveal the functional properties of neurons, the processing mechanisms within the central nervous system, and the clinical treatment of brain diseases.
关键词： Bioelectronics,Biosensor,Electrophysiological recording,Intracellular recording,Extracellular recording,Nanowire
更新于2025-09-10 09:29:36
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Improving detection efficiency of superconducting nanowire single-photon detector using multilayer antireflection coating
摘要： Optical cavity with backside optical coupling is one of the prevalent optical structures for superconducting nanowire single photon detector. A single layer anti-re?ection coating (ARC) on the backside of the substrate is often adopted to enhance the transmittance to the substrate. We here apply a multilayer ARC to further increase the transmittance from 94.5% to 99.5%. An NbTiN SNSPD made on such a substrate with cavity structure presents a system detection ef?ciency of 90.1% at a dark count rate (DCR) of 100 Hz, which is the best value reported for backside optical coupled SNSPD at 1550 nm. It shows a timing jitter of ～40.7 ps and the recovery time constant of ～22.9 ns.
关键词： superconducting nanowire single-photon detector,multilayer antire?ection coating,detection efficiency
更新于2025-09-10 09:29:36
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A Low-Cost Stable SERS Substrate Based on Modified Silicon Nanowires
摘要： In this paper, we report fabrication of a simple, stable, low-cost, and easy-to-fabricate substrate for surface enhanced Raman spectroscopy (SERS) applications. Silicon nanowires are one of the widely used nanostructures in different fields of nanotechnology. Through creating and varying the gap between nanowires and reducing their filling ratio and tapering, silicon nanowires are converted to applicable SERS substrates. Furthermore, the effects of annealing and post-KOH etching on these silver-coated silicon nanowire substrates are examined. It is shown that the applied processes remarkably enhance the captured Raman signal. For samples etched with KOH method, an optimized etching time at which the Raman signal reaches its maximum value is obtained as well. Finally, an ultra-high enhancement in the Raman signal is obtained.
关键词： Silicon nanowire,Surface-enhanced Raman spectroscopy,SERS substrates
更新于2025-09-10 09:29:36
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Design and analysis of electrostatic-charge plasma based dopingless IGZO vertical nanowire FET for ammonia gas sensing
摘要： In this paper, Dopingless Gate All Around (GAA) Vertical Nanowire Field Effect Transistor (VNWFET) is designed with artificial material Indium Gallium Zinc Oxide (IGZO) as a channel material. IGZO channel has high electron mobility compared to more traditional amorphous semiconductors. In VNWFETs, since the channel length (Lch) is characterized vertically, it can be relaxed without area penalty on-chip, which in turn also allows some relaxation in the nanowire diameter while keeping optimum short-channel-effects control. Electrostatic-Charge Plasma technique is used to form a source-drain region on an intrinsic body of IGZO material. At the source side, the N+ region is formed by selecting the appropriate work function of the metal electrode, and at the drain side, the N+ region is formed by giving biasing to the metal electrode. N+ channel dopingless VNWFET with the catalytic metal gate is proposed for ammonia gas sensing. Cobalt, Molybdenum, and Ruthenium are used as a gate electrode in ammonia gas detection due to their high reactivity towards ammonia. Also, we have compared their ON and OFF sensitivity of the proposed device toward the gas adsorption. Due to the presence of gas on the gate, the metal work function of gate metal changes which varies the OFF-current (IOFF), ON-current (ION) and Threshold voltage (Vth) as these are considered as sensitivity parameters for sensing the ammonia gas molecules. The dimensional parameters (radius, and length) and dielectric materials are varied to check the change in device sensitivities. Results show that as the work function varies increases 50, 100, 150, 200meV and 250meV for catalytic metal at the gate, the sensitivity is increased.
关键词： Vertical nanowire FET (VNWFET),Indium Gallium Zinc Oxide (IGZO),Electrostatic-Charge Plasma (E-CP),Ammonia Gas sensor
更新于2025-09-10 09:29:36