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Heterojunction Internal Photoemission of λ ~ 2.8 μm by Ge/Si Core/Shell Nanowires
摘要： The photodetector of Ge/Si core/shell nanowires can detect 2.8-μm-long infrared, far beyond the absorption edge of both semiconductors, at room temperature. The device of single nanowire grown on heavily doped Si (111) shows typical rectifying behavior despite p–p isotype of nanowire and substrate. Under illumination, the present devices show large responsivity of 35 A/W at ?0.5 V. The analysis of current–voltage characteristics shows that Ge/Si nanowire on p-type silicon device follows the model of semiconductor heterojunction rather than Schottky junction. This result implies that the interface between nanowire and substrate is the main barrier of charge transport in the present nanowire infrared detector. In this paper, the parameter values of the heterojunction of nanowire and substrate are quantitatively investigated with the thermionic transport model. The analysis of the energy band structure shows that even longer wavelength infrared can be detected through the photoemission of the holes over the reduced heterojunction barrier of 0.37 eV.
关键词： Infrared detectors,photoemission,nanowire
更新于2025-09-23 15:21:01
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SET Sensitivity of Tri-Gate Silicon Nanowire Field-Effect Transistors
摘要： The SET response of SOI tri-gate silicon nanowires is investigated using direct measurements of current transients. Resulting collected charge distributions are compared to simulations in two steps: Monte-Carlo simulations of deposited energy and TCAD simulation of collected charge, using detailed description of charge generation. Good agreement with experimental data is obtained. Current simulation tools can thus be used, with minor optimization, to simulate such integrated devices. The analysis of SETs show collected charge values lower than both the charge estimated from the LET and the charge actually generated in the nanowire, revealing a limited sensitivity of nanowire devices to high LET ions.
关键词： Nanowire,SEE,Single-Event Transient,Ultra-Thin SOI,Particle-matter interaction,Single-Event Effect,Geant4,FinFET,TCAD,Multiple-gate,Simulation,SET,Experiments
更新于2025-09-23 15:21:01
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Facilitating Tip-Enhanced Raman Scattering on Dielectric Substrates via Electrical Cutting of Silver Nanowire Probes
摘要： TERS is a powerful tool for nanoscale optical characterization of surfaces. However, even after 20 years of development, the parameters for optimal TERS tips are still up for debate. As a result, routine measurements on bulk or dielectric substrates remain exceptionally challenging. Herein we help to alleviate this by using electrical cutting to strategically modify silver nanowire TERS probes. Following cutting, the tips present a large, spherical apex and are often nanostructured with numerous nanoparticles, which we argue improve light collection and optical coupling. This doubles TERS signals on a highly-enhancing, gap-mode substrate compared to our standard nanowire tips, whilst maintaining a high reproducibility and resolution. More interestingly, on a dielectric substrate (graphene on SiO2) the tips give ~7x higher signals than our standard tips. Further investigations point to the non-local nature of the enhancement using standard, smooth, TERS probes without gap-mode, making such nanostructuring highly beneficial in these cases.
关键词： electrical cutting,silver nanowire,TERS,Tip-Enhanced Raman Scattering,nanoscale optical characterization,dielectric substrates
更新于2025-09-23 15:21:01
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[IEEE 48th European Solid-State Device Research Conference (ESSDERC 2018) - Dresden (2018.9.3-2018.9.6)] 2018 48th European Solid-State Device Research Conference (ESSDERC) - Random Dopant Fluctuation and Random Telegraph Noise in Nanowire and Macaroni MOSFETs
摘要： We present a systematic investigation of random dopant fluctuations and random telegraph noise instabilities in Nanowire and Macaroni MOSFETs via 3D atomistic Monte Carlo simulations. We discuss their dependence on geometry and doping and show that different trends appear with respect to planar devices. Some unexpected results are explained in terms of 3D percolation and electrostatic integrity of the structures.
关键词： Macaroni MOSFET,Nanowire MOSFET,random telegraph noise,random dopant fluctuations
更新于2025-09-23 15:21:01
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Single GaAs nanowire based photodetector fabricated by dielectrophoresis
摘要： Mechanical manipulation of nanowires (NWs) for their integration in electronics is still problematic because of their reduced dimensions, risking to produce mechanical damage to the NW structure and electronic properties during the assembly process. In this regard, contactless NW manipulation based methods using non-uniform electric fields, like dielectrophoresis (DEP) are usually much softer than mechanical methods, offering a less destructive alternative for integrating nanostructures in electronic devices. Here, we report a feasible and reproducible dielectrophoretic method to assemble single GaAs NWs (with radius 35–50 nm, and lengths 3–5 μm) on conductive electrodes layout with assembly yields above 90% per site, and alignment yields of 95%. The electrical characteristics of the dielectrophoretic contact formed between a GaAs NW and conductive electrodes have been measured, observing Schottky barrier like contacts. Our results also show the fast fabrication of diodes with rectifying characteristics due to the formation of a low-resistance contact between the Ga catalytic droplet at the tip of the NW when using Al doped ZnO as electrode. The current-voltage characteristics of a single Ga-terminated GaAs NW measured in dark and under illumination exhibit a strong sensitivity to visible light under forward bias conditions (around two orders of magnitude), mainly produced by a change on the series resistance of the device.
关键词： chemical beam epitaxy,optoelectronics,dielectrophoresis,nanowire assembly,GaAs nanowire photodetector,nanofabrication
更新于2025-09-23 15:19:57
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Orbital Tuning of Tunnel Coupling in InAs/InP Nanowire Quantum Dots
摘要： We report results on the control of barrier transparency in InAs/InP nanowire quantum dots via the electrostatic control of the device electron states. Recent works demonstrated that barrier transparency in this class of devices displays a general trend just depending on the total orbital energy of the trapped electrons. We show that a qualitatively different regime is observed at relatively low filling numbers, where tunneling rates are rather controlled by the axial configuration of the electron orbital. Transmission rates versus filling are further modified by acting on the radial configuration of the orbitals by means of electrostatic gating, and the barrier transparency for the various orbitals is found to evolve as expected from numerical simulations. The possibility to exploit this mechanism to achieve a controlled continuous tuning of the tunneling rate of an individual Coulomb blockade resonance is discussed.
关键词： quantum dot,InAs/InP,nanowire,Coulomb blockade,tunnel barrier,electron tunneling rate
更新于2025-09-23 15:19:57
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Synthesis of brass nanowires and their use for organic photovoltaics
摘要： Preponderant electric conductivity, high transmittance properties, and large natural abundance of its main component are striking features of copper nanowire (Cu NW)-based thin films. Because they are easily synthesized via low-cost solution-based processes, copper nanowires are considered an affordable next-generation conductor for transparent electrodes. Copper nanowire applications are expected to become more popular over the next decade. However, copper nanowire itself has a tremendously high surface-to-volume ratio and an abundance of surface atoms which lead to its high reactivity with the external environment. This reactivity presents a challenge for the improvement the long-term stability of copper nanowires, as it directly affects their applications. This novel study demonstrates a process to protect copper nanowires with an ultrathin stable brass layer-Cu/Brass NWs. The final product exhibited a high performance comparable to commonly used electrodes with a low sheet resistance of 30 Ω/sq at 89% transparency. Moreover, the Cu/Brass NWs resisted oxidation corrosion as the amplitude resistance fluctuated only around 3 Ω/sq for 30 days. For performance verification, an organic solar cell was fabricated using a Cu/Brass NW-based transparent electrode. It yielded an efficiency of 5.85%, reaching nearly that of a conventional cell using indium tin oxide. This demonstrates that Cu/Brass NWs are very promising for future application in low-cost optoelectronic devices.
关键词： Transparent electrode,Copper nanowire,Copper/brass nanowires,Electroless Zn plating,Organic solar cell
更新于2025-09-23 15:19:57
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Enhanced current density of anatase TiO2 nanowire arrays by interface connection modulation in flexible quantum dot sensitized solar cells
摘要： The stability and photovoltaic conversion efficiency are very important issues for the industry application of flexible solar cells, which have been seriously limited by the interface connection of basic photo-electrodes in solar cells. Here, one-dimensional TiO2 nanowire arrays films were employed as photo-electrodes of flexible solar cells, which have modulated interface connection of the photo-electrodes by introducing small size of nanoparticles and heating pressure process. The charge generation and separation properties of photo-electrodes have been influenced, which may be attributed by the changes on band energy of small size of nanoparticles in photo-electrodes. With the improvement on the interface connection in the photo-electrodes, the charge transfer property has been effectively improved, which have exhibited a higher current density value of the solar cells, achieving photovoltaic conversion efficiency enhancement from 2.55% to 3.90%. Moreover, there have no obvious changes on the photovoltaic conversion efficiency of these flexible QDSSCs solar cells under the curling condition.
关键词： Anatase TiO2 nanowire arrays,Flexible quantum dot sensitized solar cell,Interface connection,Photovoltaic performance enhancement,Small size of nanoparticles,Heating pressure
更新于2025-09-23 15:19:57
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Ferroelectric properties and phase transitions of high performance vertically aligned KNN nanowire-arrays grown by pulsed laser deposition
摘要： Pulsed laser deposition (PLD) was used to synthesize piezoelectric nanowire-arrays of K0.5Na0.5NbO3 (KNN) on Pt/TiO2/SiO2/Si substrates. These arrays were successfully prepared by using two different deposition conditions than the previously reported for KNN. KNN with orthorhombic structure and minority secondary phases were identified by XRD. Ferroelectric and Piezoelectric properties were confirmed by piezoresponse force microscopy, and showed that nanowire-arrays have an improvement in their effective piezoelectric coefficient of d33eff = 94.6 pm/V and 133.6 pm/V, higher than previously reported coefficients. Pulsed laser photoacoustic technique was used to analyze the phase transition temperatures and they showed a phase transition (O-T) at ～170 ?C and a phase transition (T-C) at ～360 ?C, lower temperatures than those found for bulk ceramics. Furthermore, it was identified the presence of minor amount of secondary ferroelectric phase (K4Nb6O17).
关键词： Phase transitions,KNN nanowire-arrays,Ferroelectric properties,Pulsed laser deposition,Piezoelectric coefficient
更新于2025-09-23 15:19:57
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Multiplexed Single-Photon Source Based on Multiple Quantum Dots Embedded within a Single Nanowire
摘要： Photonics-based quantum information technologies require efficient, high emission rate sources of single photons. Position-controlled quantum dots embedded within a broadband nanowire waveguide provide a fully scalable route to fabricating highly efficient single photon sources. However, emission rates for single photon devices are limited by radiative recombination lifetimes. Here we demonstrate a multiplexed single photon source based on a multi-dot nanowire. Using epitaxially grown nanowires, we incorporate multiple energy-tuned dots, each optimally positioned within the nanowire waveguide, and providing single photons with high efficiency. This linear scaling of the single photon emission rate with number of emitters is demonstrated using a five-dot nanowire with an average multiphoton emission probability of < 4% when excited at saturation. This represents the first ever demonstration of multiple single photon emitters deterministically incorporated in a single photonic device, and is a major step towards achieving GHz single photon emission rates from a scalable multi-quantum dot system.
关键词： nanowire,single photon source,multiplexing,quantum dot
更新于2025-09-23 15:19:57