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Gas Sensing Characterization of Single-Nanowire Sensor Array Systems Based on Non-Functionalized and Pt-Functionalized Tungsten Oxide
摘要： Here we present the gas sensing characterization of single-nanowire sensor array systems based on either non-functionalized or Pt-functionalized single tungsten oxide nanowires towards various concentrations of nitrogen dioxide and ethanol. The sensor systems demonstrate stable and reproducible responses to the tested analytes, showing consistency with previous systems based on multiple-nanowire based films and validating the fabrication process of these devices.
关键词： sensor array,single-nanowire,tungsten oxide,gas sensing
更新于2025-09-09 09:28:46
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Optical study of p-doping in GaAs nanowires for low-threshold and high-yield lasing
摘要： Semiconductor nanowires suffer from significant non-radiative surface recombination, however, heavy p-type doping has proven to be a viable option to increase the radiative recombination rate and hence quantum efficiency of emission, allowing demonstration of room-temperature lasing. Using a large-scale optical technique, we have studied Zn-doped GaAs nanowires to understand and quantify the effect of doping on growth and lasing properties. We measure the non-radiative recombination rate (knr) to be (0.14 ± 0.04) ps?1 by modelling the internal quantum efficiency (IQE) as a function of doping level. By applying a correlative method, we identify doping and nanowire length as key controllable parameters determining lasing behavior, with reliable room-temperature lasing occurring for p ?3 × 1018 cm?3 and lengths ? 4 μm. We report a best-in-class core-only near-infrared nanowire lasing threshold of ～ 10 μJ cm?2 , and using a data-led filtering step, we present a method to simply identify sub-sets of nanowires with over 90% lasing yield.
关键词： Doping,PL,III-V Nanowire lasers
更新于2025-09-09 09:28:46
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Nanowire-Based Josephson Junctions
摘要： The combination of superconductivity and surface states in Dirac semimetal can produce a 4π-periodic supercurrent in a Josephson junction configuration, which can be revealed by the missing of odd Shapiro steps (especially the n ? 1 step). However, the suppression of the n ? 1 step is also anticipated in the high-power oscillatory regime of the ordinary 2π-periodic Josephson effect, which is irrelevant to the 4π-periodic supercurrent. Here, in order to identify the origin of the suppressed n ? 1 step, we perform the measurements of radio frequency irradiation on Nb–Dirac semimetal Cd3As2 nanowire–Nb junctions with continuous power dependence at various frequencies. Besides the n ? 1 step suppression, we uncover a residual supercurrent of first node at the n ? 0 step, which provides a direct and predominant signature of the 4π-periodic supercurrent. Furthermore, by tuning the gate voltage, we can modulate the surface and bulk state contribution and the visibility of the n ? 1 step. Our results provide deep insights to explore the topological superconductivity in Dirac semimetals.
关键词： surface states,Cd3As2 nanowire,topological superconductivity,4π-periodic supercurrent,Josephson junctions
更新于2025-09-09 09:28:46
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Nanodisc decorated W-WOx suspended nanowire: A highly sensitive and selective H2S sensor
摘要： In this work we report room temperature synthesis of plasma oxidized, suspended tungsten-tungsten oxide (W-WOx) core-shell nanowire for sensing ppb level H2S. The electric field modulation at the W-WOx interface of the core-shell nanowire strongly influences the sensing performance and brings down the operating temperature all the way down to 50°C, compared to completely oxidized (WOx) nanowire. The optimum interface ratio (W/WOx) of the nanowire shows response of 90.4% (1 ppm) with 6 months of response stability and excellent selectivity. The limit of detection of 10 ppb with response and recovery time of 4 s and 46 s respectively is achieved. To enhance the response further, we utilize nanostructuring on top of nanowire, using nanodiscs of 20 nm, 50 nm and 100 nm diameter and 10 nm height. The nanowire with nanodiscs of 20 nm diameter shows the high repeatable response of 12529% (1 ppm) at 150°C and fast response and recovery times of 12 s and 19 s with detection limit of 0.5 ppb. As we switch from unpatterned to patterned nanowire the observed change in H2S sensing characteristics, indicates that the core-shell nanowire behaviour makes a transition from p-type to n-type. Extensive material characterization is done using UV-Vis spectroscopy, XPS and TEM.
关键词： plasma oxidation,selectivity,Core-shell nanowire,nanodiscs,suspended
更新于2025-09-09 09:28:46
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[IEEE 2018 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD) - Austin, TX, USA (2018.9.24-2018.9.26)] 2018 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD) - Toward more realistic NEGF simulations of vertically stacked multiple SiNW FETs
摘要： We present quantum transport simulation results of vertically stacked multiple silicon nanowire (SiNW) FETs based on the non-equilibrium Green’s function (NEGF) method. In order to consider more realistic device conditions such as complex geometry of the multi-channel FETs and various carrier scattering processes, we improved physical models and numerical techniques for the NEGF simulations.
关键词： non-equilibrium Green’s function (NEGF),quantum transport,multiple nanowire FET
更新于2025-09-09 09:28:46
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Quantum confinement chemistry of CdS QDs plus hot electron of Au over TiO2 nanowire protruding to be encouraging photocatalyst towards nitrophenol conversion and ciprofloxacin degradation
摘要： Solar light harvesting science is ascertained to be the topmost effective green technique in alleviating environmental pollutants. In this respect, we report a visible light active TiO2/Au/CdS QDs nanocomposite which manifested upgraded photocatalytic activity towards the transformation of 2-nitrophenol, 4-nitrophenol, and degradation of ciprofloxacin. Here, TiO2 nanowire is synthesized by a molten flux method with high product yield and crystallinity with organized dimensions. Au nanoparticles are successfully integrated in between TiO2-CdS composite by Reverse Turkevich method. The prepared composites are meticulously characterized by different physical and optoelectronic techniques to inspect the crystal structure, phase purity, optical properties, nanostructured morphology and electrochemical properties. The plasmonic direct hot electron transfer (DET) mechanism is confirmed from UV-Vis DRS spectra. The prepared composite produces 2.98 mA/cm2 of current density under light irradiation. A Longer lifetime of electrons is found from Bode phase plot i.e. 97.4 μs for TiO2/1%Au/3%CdS QDs owing to the integrative cooperation effect of high aspect ratio of TiO2 nanowire, quantum size effect of CdS and the direct hot electron transfer by Au nanoparticle.
关键词： TiO2 nanowire,2-nitrophenol,DET,4-nitrophenol,ciprofloxacin,CdS QDs
更新于2025-09-09 09:28:46
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Selectivity map for molecular beam epitaxy of advanced III-V quantum nanowire networks
摘要： Selective area growth is a promising technique to enable fabrication of scalable III-V nanowire networks required to test proposals for Majorana-based quantum computing devices. However, the contours of the growth parameter window resulting in selective growth remain undefined. Herein, we present a set of experimental techniques which unambiguously establish the parameter space window resulting in selective III-V nanowire networks growth by molecular beam epitaxy. Selectivity maps are constructed for both GaAs and InAs compounds based on in situ characterization of growth kinetics on GaAs(001) substrates, where the difference in group III adatom desorption rates between the III-V surface and the amorphous mask area is identified as the primary mechanism governing selectivity. The broad applicability of this method is demonstrated by successful realization of high quality InAs and GaAs nanowire networks on GaAs, InP, and InAs substrates of both (001) and (111)B orientations as well as homoepitaxial InSb nanowire networks. Finally, phase coherence in Aharonov-Bohm ring experiments validates the potential of these crystals for nanoelectronics and quantum transport applications. This work should enable faster and better nanoscale crystal engineering over a range of compound semiconductors for improved device performance.
关键词： GaAs,selectivity,selective area growth,epitaxy,InAs,III-V nanowire,molecular beam epitaxy
更新于2025-09-09 09:28:46
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Nanowire Growths, and Mechanisms of These Growths for Developing Novel Nanomaterials
摘要： Nanowire nanoelectronics depends largely on nanowire materials characteristics. The nanowires are grown by a number of different mechanisms. A comparative and comprehensive investigation of nanowires by these mechanisms has been carried out to address the nanowire characteristics best suited to nanoelectronics. The development and optimization of nanowire processing techniques for viable nanowire nanoelectronics have also been elucidated. The fundamentals of the growth mechanisms that lead to the best possible nanowires have been evaluated, as well. Among various mechanisms, the vapor–liquid–solid (VLS) mechanism is the oldest. It is most widely employed mechanism for nanowire growth. Challenges to the VLS nanowires have been discussed. Attributes of nanowires by the self-catalytic growth (SCG) have been explored. The details of the growth conditions of the SCG mechanism have been explained. Photoluminescence characteristics of nanowires by various mechanisms have been compared. This comparison sheds light on the relative strengths of these mechanisms. Control of growth directions, in situ arrays of nanowire self-organization, vertically aligned positioning, nanowire quality, nanowire contamination; seed/substrate mismatch interface states, etc. are the keys to nanowire applicability to nanoelectronics, which have been described. The fundamentals of various issues such as self-organization, growth criteria, Ostward ripening, Stranski–Krastanov growth mode, etc. have been articulated. Defects, dislocations, and stacking faults are very detrimental for nanotechnology. Relative strengths and weaknesses of various mechanisms based on nanowire defects, dislocations, and stacking faults have been elaborated.
关键词： Mohammad’s Hypothesis,Growth Mechanisms,Nanowire Growths,Ostwald Ripening
更新于2025-09-04 15:30:14
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25 nm Single-Crystal Silicon Nanowires Fabricated by Anisotropic Wet Etching
摘要： We report a top-down method for fabricating ultra-high aspect ratio single-crystal silicon nanowires. The fabrication method is based on the standard photolithography technique and anisotropic wet etching of the single-crystal silicon in KOH solution. SiO2 mask nanolines used for patterning single-crystal silicon nanowires are formed by the undercut etching of thin SiO2 layer in buffered hydrofluoric solution. The minimum width of the SiO2 mask nanolines are 50 nm. The length of SiO2 mask nanolines is 2 cm. The single-crystal silicon nanowires have been successfully transferred from the SiO2 mask nanolines by KOH anisotropic wet-chemical etching. The minimum width of the silicon nanowire has obtained to be 25 nm. The fabricated single-crystal silicon nanowires have trapezoidal and triangular cross sections, which are useful for applications in nanoelectronic and nanophotonic elements.
关键词： All Wet Chemical Etching,Wafer-Scale Fabrication,Single-Crystal Silicon Nanowire,Photolithography
更新于2025-09-04 15:30:14
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Micro-Raman Spectroscopy in Self-Catalyzed Indium Phosphide Nanostructures: Morphology and Substrate Effects
摘要： We report the effect of morphology and substrate of self-catalyzed indium phosphide (InP) nanostructures on phonon vibration modes. Using liquid indium as a catalyst, we grew self-catalyzed InP nanocones and nanopillars on single crystal substrates of InP(111)B, Si(111), and Si(100) via metal-organic chemical vapor epitaxy. Due to crystal symmetry breaking in one-dimensional nanostructure, longitudinal-optical (LO) and transverse-optical (TO) phonon modes are clearly resolved with the strong anisotropic behavior. Broadening and downshift of LO phonon modes are found to be sensitive to the morphology (i.e., aspect ratio and surface-to-volume ratio) and crystal structure (i.e., Wurtzite and Zinc Blende) of the as-grown nanostructures. This work demonstrated that Raman spectroscopy provides statistical insights on the quality of as-grown nanostructures (i.e., growth orientation, crystal structures, and the presence of structural defects) without destroying samples.
关键词： VLS Process,MOVPE,InP Nanowire,Raman Spectroscopy,Self-Catalyst
更新于2025-09-04 15:30:14