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Microwave-Assisted Tunneling in Hard-Wall InAs/InP Nanowire Quantum Dots
摘要： With downscaling of electronic circuits, components based on semiconductor quantum dots are assuming increasing relevance for future technologies. Their response under external stimuli intrinsically depend on their quantum properties. Here we investigate single-electron tunneling in hard-wall InAs/InP nanowires in the presence of an off-resonant microwave drive. Our heterostructured nanowires include InAs quantum dots (QDs) and exhibit different tunnel-current regimes. In particular, for source-drain bias up to few mV Coulomb diamonds spread with increasing contrast as a function of microwave power and present multiple current polarity reversals. This behavior can be modelled in terms of voltage fluctuations induced by the microwave field and presents features that depend on the interplay of the discrete energy levels that contribute to the tunneling process.
关键词： Microwave-Assisted tunneling,Single-electron tunneling,Hard-Wall InAs/InP nanowire,Quantum Dots,Coulomb diamonds
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Performance and Degradation Evaluation of PV Modules on the Substring Level by an In-Situ Electronic Device
摘要： We report silicon ?eld emitter arrays (FEAs) that demonstrate current densities >100 A/cm2 at gate–emitter voltages <75 V. These are the highest current densities reported for a semiconductor FEA, and approach the current densities of Spindt-type metal cathodes. We achieved these results using a new device structure that employs high-aspect-ratio silicon nanowire current limiters in series with each emitter tip to address the major failure mechanisms in FEAs. These current limiters mitigate emitter tip failure due to joule heating thus allowing for higher reliability. We employed a novel fabrication process to produce small gate apertures (≈350 nm) that are self-aligned to the ?eld emitter tip enabling device operation at >100 A/cm2 with gate-to-emitter voltages that are less than 75 V. These FEAs demonstrate performance that has the potential to enable smaller, more ef?cient, and high-power vacuum electronics.
关键词： FEAs,nanowires,Field emission arrays,silicon FEAs,silicon tips,silicon nanowire current limiters
更新于2025-09-19 17:13:59
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Carrier lifetime exceeding 81 ns in single crystalline perovskite nanowires enable large on-off ratio photodetectors
摘要： Single crystalline perovskite nanowires are ideal candidates for photodetection and other optoelectronic applications due to their unique advantage of allowing the manipulation of light and carriers in nanoscale via the naturally formed boundaries. Although significant efforts have been made to grow high quality single crystalline perovskite nanowires, their carrier life times are much shorter than their bulk single crystal counterparts. Here, based on the surface initiated solution growth method with fine kinetic control, we fabricate high quality single crystalline MAPbI3 nanowires with the carrier life time as long as 81 ns, which outperforms the performances of all other solution processed single crystalline MAPbI3 nanowires. The as-prepared metal-semiconductor-metal photodetector has an extremely low dark current of 180 fA under 1 V bias, and a current of 340 pA under illumination of 10.2 mW/cm2, corresponding to an on-off current ratio of 1880, which is the largest on-off ratio in photodetectors based on MAPbI3 nanowires without any passivation treatment. Such superior performance is attributed to the long carrier life time of the as-grown MAPbI3 nanowires with reduced grain boundaries. The realized high performance MAPbI3 nanowire photodetector would find potential applications in imaging sensors.
关键词： Nanowire,Perovskite,Single-crystalline,Photodetection,Carrier life time
更新于2025-09-19 17:13:59
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Halogen Vacancies Enable Ligand‐Assisted Self‐Assembly of Perovskite Quantum Dots into Nanowires
摘要： Interest has been growing in defects of halide perovskites in view of their intimate connection with key material optoelectronic properties. In perovskite quantum dots (PQDs), the influence of defects is even more apparent than in their bulk counterparts. By combining experiment and theory, we report herein a halide-vacancy-driven, ligand-directed self-assembly process of CsPbBr3 PQDs. With the assistance of oleic acid and didodecyldimethylammonium sulfide, surface-Br-vacancy-rich CsPbBr3 PQDs self-assemble into nanowires (NWs) that are 20–60 nm in width and several millimeters in length. The NWs exhibit a sharp photoluminescence profile ( (cid:2) 18 nm full-width at-half-maximum) that peaks at 525 nm. Our findings provide insight into the defect-correlated dynamics of PQDs and defect-assisted fabrication of perovskite materials and devices.
关键词： self-assembly,perovskite quantum dot,halide vacancy,nanowire,CsPbBr3
更新于2025-09-19 17:13:59
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An Assembled Ordered W18O49 Nanowire Film with high SERS Sensitivity and Stability for the detection of RB
摘要： In this work, a novel ordered nanowire film composed of non-stoichiometric semiconductor metal oxide, W18O49, was assembled by a three-phase-interface approach. The prepared W18O49 nanowires possess relatively uniform morphologies with average diameter of about 10 nm. When employed as the SERS substrate for the detection of rhodamine B (RB), the ordered W18O49 nanowire film calcined in Ar/H2 (W18O49-H2) exhibited stronger SERS signal than W18O49 nanowire films which resulted from the existence of more oxygen vacancies due to the reduction effect of H2. The SERS detection limit of RB on W18O49-H2 nanowire films reached 10-7 M. And more importantly, the W18O49-H2 nanowire film SERS substrate possessed outstanding reproducibility for detecting RB because of the ordered as well as stable morphology, reflecting in the low relative standard deviation (RSD) (9.7%). Therefore, as a new non-noble metal SERS substrate, the W18O49-H2 nanowire film provides an important inspiration for its wide application in the detection of pollutants.
关键词： reproducibility,ordered W18O49 nanowire film,SERS substrate,RB detection
更新于2025-09-19 17:13:59
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Charge transfer in Nanowire-Embedded PEDOT:PSS and Planar Heterojunction Solar Cells
摘要： Hybrid metallic nanowires-embedded, highly conductive poly(3,4-ethylenedioxy thiophene):polystyrenesulfonate (PEDOT:PSS) with synergetic properties is indispensable for enhancing the performances of conductive polymer-based electronic devices. Here we report embedment of silver nanowires (AgNWs), with diameter ~100 nm and a high concentration (500 mg/ml) of nanowires dispersed in either ethanol or isopropanol, in PEDOT:PSS and compare the effects of the nanowire-dispersing solvents as well as its thicker diameter and high concentration on the overall properties, and particularly its charge transfer characteristics and planar heterojunction solar cell (HSC) properties. Furthermore, electrostatic force microscopy is applied to elucidate the direct charge transfer from AgNWs to the PEDOT:PSS matrix. The AgNW-embedded PEDOT:PSS-based planar HSCs show a very high open-circuit voltage of over 638 mV and a high power conversion efficiency greater than 15.3%, and without any significant influence from the AgNWs dispersing solvents. While charge transfer in PEDOT:PSS without AgNWs occurs through the conducting PEDOT grains, enhanced charge transfer is realized in AgNW-embedded PEDOT:PSS with charge transport from PEDOT grains to AgNWs and then to PEDOT grains before reaching the top electrode in the HSC. The AgNW-embedded PEDOT:PSS hybrid materials pave a simple way to enhance the charge transfer performance in not only HSCs but also other hybrid or heterojunction electronics.
关键词： heterojunction solar cell,poly(3,4-ethylenedioxy thiophene):polystyrenesulfonate or PEDOT:PSS,silver nanowire,Conducting polymer,electrostatic force microscopy,charge transfer
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE International Conference on Space Optical Systems and Applications (ICSOS) - Portland, OR, USA (2019.10.14-2019.10.16)] 2019 IEEE International Conference on Space Optical Systems and Applications (ICSOS) - Real Time Photon-Counting Receiver for High Photon Efficiency Optical Communications
摘要： We present a scalable design for a photon-counting ground receiver based on superconducting nanowire single photon detectors (SNSPDs) and field programmable gate array (FPGA) real-time processing for applications to space-to-ground photon starved links, such as the Orion EM-2 Optical Communication Demonstration (O2O) [1], and future deep space or low transmitter power missions. The receiver is designed to receive a serially concatenated pulse position modulation (SCPPM) waveform [2], which follows the Consultative Committee for Space Data Systems (CCSDS) Optical Communications Coding and Synchronization Red Book standard [3]. The receiver design uses multiple individually fiber coupled, 80% detection efficiency commercial SNSPDs in parallel to scale to a required data rate, and is capable of achieving data rates up to 528 Mbps. For efficient fiber coupling from the telescope to the array of parallel detectors that can be scaled both to telescope aperture size and the number of detectors, we use either a single mode fiber (SMF) photonic lantern or a few-mode fiber (FMF) photonic lantern [4]. In this paper we give an overview of the receiver system design, the characteristics of the photonic lanterns, the performance of the SNSPDs, and system level tests. We show that 40 Mbps can be received using a single SNSPD, and discuss aspects for scaling to higher data rates.
关键词： few-mode fibers,superconducting nanowire,optical communications,single photon detectors
更新于2025-09-19 17:13:59
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Role of nanowire length on the performance of self-driven NIR Photodetector based on mono/bi-layer graphene (camphor)/Si-Nanowire Schottky junction
摘要： In this article, we have demonstrated a solid carbon source such as camphor as a natural precursor to synthesize a large area mono/bi-layer graphene (MLG) sheet to fabricate nanowire junction based near infrared photodetectors (NIRPDs). In order to increase the surface-to-volume ratio, we have developed Si-nanowire arrays (SiNWAs) of varying lengths by etching up to 2V with a fast rise and decay time of 34/13 ms. A tremendous enhancement has been witnessed from 36 μA/W to 22 mA/W in the responsivity at 0V for MLG/30 min SiNWAs than planar Si. Then, the camphor based MLG/Si and MLG/SiNWAs schottky junction photodetectors have been fabricated to achieve efficient response with self-driven properties in the near infrared (NIR) regime. Due to a balance between light absorption capability and surface recombination centres, devices having SiNWAs obtained by etching for 30 min shows a better photoresponse, sensitivity and detectivity. Fabricated NIRPDs can also be functioned as self-driven device which are highly responsive and very stable at low optical power signals indicating an important development of self-driven NIRPDs based on camphor based MLG for future optoelectronic devices.
关键词： Si nanowire arrays,Graphene,Camphor,Responsivity and near infrared photodetectors.
更新于2025-09-19 17:13:59
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Electrostatically Doped Silicon Nanowire Arrays for Multispectral Photodetectors
摘要： Nanowires have promising applications as photodetectors with superior ability to tune absorption with morphology. Despite their high optical absorption, the quantum efficiencies of these nanowire photodetectors remain low due to difficulties in fabricating a shallow junction using traditional doping methods. As an alternative, we report non-conventional radial heterojunction photodiodes obtained by conformal coating of indium oxide layer on silicon nanowire arrays. The indium oxide layer has a high work function which induces a strong inversion in the silicon nanowire and creates a virtual p-n junction. The resulting nanowire photodetectors show efficient carrier separation and collection leading to an improvement of quantum efficiency up to 0.2. In addition, by controlling the nanowire radii, the spectral response of the In2O3/Si nanowire photodetectors are tuned over several visible light wavelengths, creating a multispectral detector. Our approach is promising for the development of highly-efficient wavelength selective photodetectors.
关键词： electrostatic doping,nanowire photodetectors,multispectral,photosensors,silicon nanowire,dopant-free,radial junction
更新于2025-09-16 10:30:52
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - A Compact Butler Matrix Design Based on Metallic Nanowire Filled Membrane Technology and Tunable Phase Shifter at 160 GHz
摘要： This paper presents the design of a planar miniaturized 4x4 Butler matrix, with implementation of 4 tunable 135° delay line phase shifters for a 160 GHz application. The Butler matrix and phase shifters are both realized with a metallic nanowire filled slow-wave alumina membrane microstrip line to miniaturize the size. Tunability is achieved by filling in a microwave liquid crystal. Comparing with commonly used corporate feed network, the simulation results show such a Butler matrix with 135°-phase shifters has less insertion loss and reduced size.
关键词： 160 GHz,slow-wave alumina membrane,Butler matrix,metallic nanowire,phase shifters,liquid crystal
更新于2025-09-16 10:30:52