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Analysis of Recombination Processes in Polytype Gallium Arsenide Nanowires
摘要： Here we investigate recombination in polytype gallium arsenide (GaAs) nanowires (NWs) for photovoltaic applications, through photoluminescence studies coupled with rate equation analysis. Polytype NWs exhibit switching between zinc-blende (ZB) and wutrzite (WZ) crystal phases along the wire due to rotational twinning during self-catalyzed growth. When photons are absorbed in polytype NWs, electrons and holes separate: in the simplest case, electrons quickly thermalize to the band-edge of the ZB phase, while holes thermalize to the band-edge of the WZ phase, recombining indirectly in space across the type II offset. The recombination mechanisms of this system are investigated experimentally through time-resolved photoluminescence (TRPL) at liquid helium temperature, and time-integrated photoluminesence (TIPL) at various temperatures, for the baseline case of AlGaAs capped GaAs NWs. The effects of the surface recombination on sub-bandgap transitions are also investigated using Al2O3 and no capping at the surface. We infer that carriers quickly thermalize to the spatially closest, lowest energy level, where they radiatively recombine across a sub-bandgap energy gap at a slower radiative rate than band-to-band. We use a rate equation model to investigate different configurations of polytype defects along the wire, including the effects of the surface and temperature, which compares well with experiment considering spatially indirect recombination between different polytypes, and defect-related recombination due to twin planes and other defects.
关键词： Nanowires,Polytypism,Next Generation Photovoltaics,Modeling
更新于2025-09-10 09:29:36
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A Wearable Second Skin-Like Multifunctional Supercapacitor with Vertical Gold Nanowires and Electrochromic Polyaniline
摘要： A Wearable Second Skin-Like Multifunctional Supercapacitor with Vertical Gold Nanowires and Electrochromic Polyaniline. An ideal wearable/implantable bio-diagnostics can be powered by second skin-like energy devices in that they offer advantages such as conformal attachment/integration, lightweightness, and moduli-matching properties. Past several years have witnessed encouraging progresses in soft stretchable supercapacitors by various material combinations and design strategies; however, it remains nontrivial to achieve highly flexible high-performance supercapacitors in a skin-thin layout yet with multifunctionality. Here, such a second skin-like electrochromic supercapacitor is demonstrated using self-assembled vertical gold nanowires (v-AuNWs) and electrodeposited polyaniline (PANI). The v-AuNW film is highly conductive yet offers great flexibility and deformability, while PANI plays a dual role in enhancing capacitance and as charge/discharge-level indicator. The assembled supercapacitors offer superior skin-conformability and could achieve an areal specific capacitance of 11.76 mF cm?2 (scan rate of 10 mV s?1) with high durability. A second skin-like wearable tattoo energy device can be designed with negligible performance deterioration under multiple hand movements and skin deformations.
关键词： vertical gold nanowires,skin-conformable,multifunctional,electrochromic
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Coherent Dynamics of Nanowire Force Sensors
摘要： We describe the use of grown nanowires as scanning directional force sensors. Two orthogonal flexural modes are used to demonstrate vectorial sensing of electric and magnetic fields. Furthermore, we show that the modes can be strongly coupled by demonstrating Rabi oscillations. These results open the way to implement coherent control and frequency stabilization in nanomechanical force and mass sensors.
关键词： Scanning probe microscopy,nanomechanics,quantum sensing,nanowires,frequency fluctuations
更新于2025-09-10 09:29:36
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[Nanostructure Science and Technology] Nanowire Electronics || Metal-Semiconductor Compound Contacts to Nanowire Transistors
摘要： Semiconductor nanowires [1–4] are promising building blocks for next-generation ultrascaled devices for electronic [5–7] and optoelectronic [8–10] applications. An important aspect for the development, maturity, and ef?ciency of these ultrascaled devices is the detailed understanding of and control over the phase transformation that accompanies the formation of their compound contacts for lithography-free self-aligned gate design [11, 12]. The term “compound” here refers to the formed phases that have ?xed stoichiometry between metal and semiconductor elements, to be distinguished from the broader “alloy” term for phases that may include nonstoichiometric or amorphous structure. This distinction is important because the formation of a low resistance, crystalline, and thermally stable compound contact is most preferred for realizing reliable functionality in ultrascaled semiconductor transistors. Usually, the phase of compound contact and its interfacial property with semiconductor nanowire (NW) can largely affect the band alignment and charge injection in NW channels. This demands the detailed studies of the metal-semiconductor solid-state reactions, including the formed compound phases, reaction kinetics, and their correlation to the device performances. In this book chapter, we provide a thorough discussion of these three topics.
关键词： metal-semiconductor solid-state reactions,compound contacts,reaction kinetics,phase transformation,Semiconductor nanowires,device performances
更新于2025-09-10 09:29:36
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[Nanostructure Science and Technology] Nanowire Electronics || Nanowires for Triboelectric Nanogenerators
摘要： Currently, the personal portable electronics are powered by traditional batteries. However, as the electronic elements and power consumption increase, the power source has become an issue because it is impractical to frequently recharge or replace the batteries. Especially, for implanted and biomedical electronic systems, to replace the power sources is unrealistic. Moreover, list of the shortcomings of the conventional power sources includes not only the limited capacity but also environmental pollution and possible explosion and health hazards. Besides, the heavy and rigid boxy batteries hinder the further development of ?exible and wearable electronics and biomedical electronics. On the other way, most of the existing sensing technologies need to be pre-supported and pre-offered electrical or optical signals to sense environmental information, which inevitably requires foreign power sources. With the increased number and density of sensing networks, the sensors that can be of low-power consumption or even self-powered will be desired for future electronic modules [1–7]. TENG was ?rst invented by Zhong Lin Wang’s group in 2012 [8]. A more and deep study and discussion about TENGs can be found in another reference book [1]. Such devices utilize the conjunction of the triboelectri?cation and electrostatic induction to convert ubiquitous mechanical energy into electricity. The devices can act as ef?cient and sustainable energy converters and providers from harvesting environment low-frequency mechanical energy, such as wind, wave, river ?ow, rain drop, human body motions, and so forth [2–6, 9]. The collected energy can be converted to electric energy sources for continuously powering electronic devices and even systems [10]. Triboelectric effect is a contact-induced electri?cation in which a material turns into electrically charged after it is physically contacted with another different kind of materials. It is a natural phenomenon, and, probably, most of the people have been experiencing the triboelectric phenomena in our daily life. However, the mechanisms and availability of triboelectri?cation were seldom to be explored [11, 12].
关键词： Flexible Electronics,Nanowires,Triboelectric Nanogenerators,Energy Harvesting,Self-powered Sensors
更新于2025-09-10 09:29:36
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Synthesis of uniform silver nanowires from AgCl seeds for transparent conductive films via spin-coating at variable spin-speed
摘要： Uniform silver nanowires (AgNWs) with high aspect ratio are significant to fabricate high-performance transparent conductive films (TCFs). In this work, AgNWs were synthesized through polyol method using AgCl as seeds. The growth mechanism of AgNWs upon AgCl particles was demonstrated, which provided a clear understanding of heterogeneous nucleation for synthesizing crystal. The amounts and the reaction time of AgCl were discussed to probe the effect on morphology of final AgNWs. Apart from that, the temperature was also tuned to provide appropriate thermal energy for synthesis of AgNWs. Uniform AgNWs with thin diameter about 52 nm and aspect ratio above 1000 were synthesized by optimizing the amounts, reaction time of AgCl and the temperature. These AgNWs were utilized to fabricate TCFs firstly through spin-coating at a variable speed. The resulting films coated at variable spin-speed largely improved the performance of films compared with those of films coated at constant spin-speed, exhibiting a low sheet resistance of 54Ω sq-1 and high transmittance of 92% at 550 nm with haze of 5.4%.
关键词： growth,AgCl,Silver nanowires,transparent conductive films,spin-coating
更新于2025-09-10 09:29:36
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Improving the stability of silver nanowire/polyimide composite films for transparent film heaters
摘要： Flexible and transparent heaters have gradually attracted considerable attention because of its widely application in defrosting or demisting windows and medical thermotherapy. The stability of the heater under ambient conditions during working is one of the important properties. In this paper, we fabricated a highly stable and transparent film heater (TFH) through a simple drop-coating approach with burying silver nanowires (AgNWs) between colorless polyimide (cPI) and polymethyl methacrylate (PMMA). The developed TFH exhibited higher stability with the resistance increasing by 17% only for the initial value of 9.6 ? after accelerating test at 105 °C and 100% relative humidity for 36 h, which was much lower than that of 83% for TFH without PMMA. Furthermore, the fabricated film heater covered with PMMA showed extreme stability in hydrogen sulfide oven. Meanwhile, there was no significant influence in the transmittance, mechanical flexibility and heating performance after coating a PMMA layer. Finally, we applied the film heater to demisting demonstration.
关键词： transparent film heaters,polyimide,polymethyl methacrylate,silver nanowires,stability
更新于2025-09-10 09:29:36
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Rapid Pulsed Light Sintering of Silver Nanowires on Woven Polyester for personal thermal management with enhanced performance, durability and cost-effectiveness
摘要： Fabric-based personal heating patches have small geometric profiles and can be attached to selected areas of garments for personal thermal management to enable significant energy savings in built environments. Scalable fabrication of such patches with high thermal performance at low applied voltage, high durability and low materials cost is critical to the widespread implementation of these energy savings. This work investigates a scalable Intense Pulsed Light (IPL) sintering process for fabricating silver nanowire on woven polyester heating patches. Just 300 microseconds of IPL sintering results in 30% lesser electrical resistance, 70% higher thermal performance, greater durability (under bending up to 2 mm radius of curvature, washing, humidity and high temperature), with only 50% the added nanowire mass compared to state-of-the-art. Computational modeling combining electromagnetic and thermal simulations is performed to uncover the nanoscale temperature gradients during IPL sintering, and the underlying reason for greater durability of the nanowire-fabric after sintering. This large-area, high speed, and ambient-condition IPL sintering process represents an attractive strategy for scalably fabricating personal heating fabric-patches with greater thermal performance, higher durability and reduced costs.
关键词： Intense Pulsed Light (IPL) sintering,woven polyester,personal thermal management,energy savings,silver nanowires
更新于2025-09-10 09:29:36
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Synthesis of TiO <sub/>2</sub> (B) and High-temperature Stable Anatase TiO <sub/>2</sub> Nanowires by Hydrothermal Method and Investigation of Photocatalytic Activity
摘要： In this study, TiO2 nanowires (TNWs) were synthesized through hydrothermal method and were characterized using X-Ray diffraction (XRD), transmission electron microscopy (TEM) and BET techniques. Monoclinic TiO2 (B) is the dominant phase of TNWs up to 600 ℃ which is completely transformed into a highly crystalline anatase phase at 800 ℃. The photocatalytic activity of TNWs, prepared at various calcination temperatures, was investigated in the removal of Rhodamine B (RhB) as an organic model pollutant. The results indicated that the photocatalytic activity of TNWs, prepared at 800 ℃ calcination temperature (TNWs-800), was better than that of other samples and even TiO2-P25 nanoparticles.
关键词： Anatase TiO2 nanowires,Photocatalytic activity,TiO2 (B),Hydrothermal method,High-temperature
更新于2025-09-10 09:29:36
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Insight into phonon scattering in Si nanowires through high-field hole transport: Impacts of boundary condition and comparison with bulk phonon approximation
摘要： The impact of how to model phonon scattering on hole transport in Si nanowires was studied based on Boltzmann’s transport equation. Boundary conditions for atomistic description of phonons in nanowires and approximation by bulk acoustic and optical phonons were analyzed in terms of their impacts on high-field hole transport. The boundary conditions for phonons influence the drift velocity and momentum relaxation time, especially at low electric field, but the energy relaxation time hardly depends on the boundary conditions. The impacts by the change of boundary conditions can be approximated by the change of the strength of acoustic phonon scattering in bulk phonon picture, though the behavior of energy relaxation and distribution function of holes can not be reproduced by bulk phonon approximation.
关键词： Si nanowires,boundary condition,bulk phonon approximation,phonon scattering,high-field hole transport
更新于2025-09-10 09:29:36