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Probing the light hole / heavy hole switching with correlated magneto-optical spectroscopy and chemical analysis on a single quantum dot
摘要： A whole series of complementary studies have been performed on the same, single nanowire containing a quantum dot: cathodoluminescence spectroscopy and imaging, micro-photoluminescence spectroscopy under magnetic field and as a function of temperature, and energy-dispersive X-ray spectrometry and imaging. The ZnTe nanowire was deposited on a Si3N4 membrane with Ti/Al patterns. The complete set of data shows that the CdTe quantum dot features the heavy-hole state as a ground state, although the compressive mismatch strain promotes a light-hole ground state as soon as the aspect ratio is larger than unity (elongated dot). A numerical calculation of the whole structure shows that the transition from the heavy-hole to the light-hole configuration is pushed toward values of the aspect ratio much larger than unity by the presence of a (Zn,Mg)Te shell, and that the effect is further enhanced by a small valence band offset between the semiconductors in the dot and around it.
关键词： molecular beam epitaxy,optical spectroscopy,EDX,semiconductors,cathodoluminescence,quantum dot,nanowires
更新于2025-11-21 11:20:48
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Highly flexible self-powered photodetectors based on core–shell Sb/CdS nanowires
摘要： Flexible photodetectors have great applications in flexible image sensors, wearable electronics and smart robots. In this work, we reported the fabrication of highly flexible self-powered photodetectors with core-shell Sb/CdS nanowires as the sensing materials. The fabricated device exhibited high Ion/Ioff ratio of 3.54×103 under zero bias, fast speed of photoresponse and great stability. An open-circuit voltage of 0.35 V was generated due to the presence of CdS and CdSb interfaces within the core-shell nanowires. Besides, the photocurrent of the flexible device is nearly invariable at various bending angles and even after thousands of bending cycles, demonstrating the excellent flexibility and bending stability. The results indicated that the self-powered photodetectors are promising candidates for future passive optoelectronic devices.
关键词： core-shell Sb/CdS nanowires,optoelectronic devices,self-powered,flexible photodetectors
更新于2025-11-21 11:03:13
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A novel Ag nanoparticles/TiO2 nanowires-based photodetector and glucose concentration detection
摘要： A unique vapour transport cum glancing angle deposition (VT-GLAD) technique was employed to fabricate titanium dioxide (TiO2) nanowires (NWs). The NWs were grown and assembled to form the clusters. Both brookite (412) and rutile (002) phase for TiO2 was obtained from X-ray diffraction (XRD). The d spacing of ~ 1.37 ? was calculated from the transmission electron microscopy (TEM) of TiO2 NWs, which corresponds to (002) crystal plane. The silver (Ag) nanoparticles (NPs) on TiO2 NWs were grown using thermal evaporation cum GLAD technique. The presence of Ag NPs on the TiO2 NWs enhanced the photoconduction as compared to bare TiO2 NWs device. The maximum photosensitivity of the Ag NPs/TiO2 NWs based device was recorded ~ 1.6 times compared to the bare TiO2 NWs based device at ? 2.5 V. The Ag NPs containing device was highly UV sensitive and maximum responsivity for the device was calculated to be ~ 2.3 A/W at 370 nm. The device also possessed high responsivity rejection (RR) ratio of ~ 6.5 between UV (370 nm) and visible (450 nm) light. The Ag NPs decorated TiO2 NWs based detector also showed response to white light. The different concentration of glucose into deionised (DI) water-based solution was detected precisely under white light illumination. The normalised (light/dark) detector current/glucose concentration value was decreased from ~ 0.19 to ~ 0.05 at ? 2.5 V, with an increase in glucose concentration into the solution from 40 mg/dl to 200 mg/dl.
关键词： photodetector,Ag nanoparticles,TiO2 nanowires,VT-GLAD technique,glucose concentration detection
更新于2025-11-21 11:01:37
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Silicon nanowire luminescent sensor for cardiovascular risk in saliva
摘要： Cardiovascular diseases are some of the today major cause of death in the world. C-reactive protein (CRP) is well known as the main biomarker related to cardiovascular risk and heart attack occurrence. The standard CRP analyses are performed in a hospital or in a biochemical laboratory with blood analysis after a long chemical and labelling preparation that require expert personnel. In this scenario, a health care analysis that can be performed by the same patient at his own home appears extremely revolutionary. In this paper, the study of an innovative sensing platform based on the luminescence at room temperature of silicon nanowires (NWs) is reported. This NWs sensor is label-free and does not require a chemical treatment of the analyte, is strongly selective to the CRP demonstrating a femtomolar limit of detection and a wide operating range. This proposed silicon sensing platform can be realized with an industrial compatible approach and permits to reveal the strategic CRP level in saliva in order to prevent a heart attack, with great advantages for the patient.
关键词： Cardiovascular risk,Saliva,C-reactive protein,Silicon nanowires,Luminescent sensor
更新于2025-11-21 11:01:37
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g-C3N4 nanosheets functionalized silicon nanowires hybrid photocathode for efficient visible light induced photoelectrochemical water reduction
摘要： We report the fabrication of hybrid Si nanowires @ g-C3N4 nanosheets based photocathode using metal assisted chemical etching and facile liquid exfoliated process. The g-C3N4 nanosheets on Si nanowires form hybrid heterojunction photocathode, which exhibits an enhanced photon induced water reduction activity enabling higher photocurrent density of 22 mA cm?2 with applied bias photocurrent conversion efficiency of 4.3% under visible light irradiation. The onset potential of cathodic photocurrent is positively shifted from 41 to 420 mV vs. RHE with the short circuit current density, Jsc of 0.50 mA cm?2 owing to superior charge transport in hybrid photocathode as compared to pristine Si nanowires for hydrogen evolving reaction at pH～7. The electrochemical impedance spectroscopy measurement elucidates the interface layer of g-C3N4 nanosheets form hybrid heterojunction with Si nanowires that result significant increment in solar water reduction activity owing to low charge transferred resistance with high life time of excited electrons in conduction band. This strategy may open to design a new low cost stable hybrid heterostructure photocathode for solar induced water reduction.
关键词： Solar water reduction,Si nanowires,Photocathode,g-C3N4 nanosheets,Interface
更新于2025-11-21 11:01:37
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Dual Management of Electrons and Photons to Get High-Performance Light Emitting Devices Based on Si Nanowires and Si Quantum Dots with Al <sub/>2</sub> O <sub/>3</sub> -Ag Hybrid Nanostructures
摘要： Silicon quantum dot (Si QD)-based light emitting devices are fabricated on Si nanowire (Si NW) arrays. Through inserting Al2O3-Ag hybrid nanostructures (Al2O3-Ag HNs) between Si NWs and Si QDs, both photoluminescence (PL) and electroluminescence (EL) are remarkably enhanced compared to the control sample. The PL enhancement can be mainly attributed to passivation effect of Al2O3 to p-type Si NWs and enlarged absorption cross-section due to the local surface plasmon resonance effect of Ag nanoparticles. The EL intensity is enhanced by 14.9-fold at the same injection current under a lower applied voltage, which may result from the high injection efficiency of electrons and the promoted waveguide effect of nanowire structures with Al2O3-Ag HNs. It is demonstrated that light emitting device performances can be well improved by careful management of both electrons and photons via controlling the interface conditions of Si NWs/Si QDs.
关键词： hybrid nanostructures,silicon nanowires,light emitting devices,silicon quantum dots
更新于2025-11-21 11:01:37
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Strong Cathodoluminescence and Fast Photoresponse from Embedded CH3NH3PbBr3 Nanoparticles Exhibiting High Ambient-Stability
摘要： This study presents a comprehensive analysis of the strong cathodoluminescence (CL), photoluminescence (PL), and photoresponse characteristics of CH3NH3PbBr3 nanoparticles (NPs) embedded in a mesoporous nanowire template. Our study revealed a direct correlation between the CL and PL emissions from the perovskite NPs (Per NPs), for the first time. Per NPs are fabricated by a simple spin coating of perovskite precursor on the surface of metal-assisted-chemically-etched mesoporous Si NWs array. The Per NPs confined in the mesopores show blue shifted and enhanced CL emission as compared to the bare perovskite film, while the PL intensity of Per NPs dramatically high compared to its bulk counterpart. A systematic analysis of the CL/PL spectra reveals that the quantum confinement effect and ultra-low defects in Per NPs are mainly responsible for the enhanced CL and PL emissions. Low-temperature PL and time-resolved PL analysis confirm the high exciton binding energy and radiative recombination in Per NPs. The room temperature PL quantum yield of the Per NPs film on the NW template was found to be 40.5 %, while that of Per film was 2.8%. The Per NPs show improved ambient air-stability than the bare film due to the protection provided by the dense NW array, since dense NW array can slow down the lateral diffusion of oxygen and water molecules in Per NPs. Interestingly, the Si NW/Per NPs junction shows superior visible light photodetection and the prototype photodetector shows a high responsivity (0.223 A/W) with a response speed of 0.32 sec and 0.28 sec of growth and decay in photocurrent, respectively, at 2V applied bias, which is significantly better than the reported photodetectors based on CH3NH3PbBr3 nanostructures. This work demonstrates a low-cost fabrication of CH3NH3PbBr3 NPs on a novel porous NW template, which shows excellent photophysical and optoelectronic properties with superior ambient stability.
关键词： Perovskite Nanoparticles,PL QY enhancement,Porous Si Nanowires,Fast Photoresponse,CL Enhancement
更新于2025-11-21 11:01:37
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Tailored nanocomposite energy harvesters with high piezoelectric voltage coefficient through controlled nanowire dispersion
摘要： Composites composed of piezoelectric nanomaterials dispersed in a flexible polymer have emerged as promising materials for highly durable and flexible energy harvesters and sensors. Although piezoelectric materials in their bulk form have a high electromechanical coupling coefficient and can efficiently convert mechanical energy to electrical energy, the ceramic form has low fracture toughness and thus they are limited in certain applications due to difficulty in machining and conforming to curved surfaces. Recently, additive manufacturing processes such as direct write, have been developed to incorporate piezoelectric nanowires into a polymer matrix with controlled alignment to realize printed piezoelectrics. Given the multiphase structure of a nanocomposite, it is possible to control the material structure such that the piezoelectric coupling and dielectric properties can be varied independently. In this paper, experimentally validated finite element (FE) and micromechanics models are developed for calculation and optimization of the piezoelectric voltage coefficient, g31, of a nanocomposite. It is shown that by using high aspect ratio nanowires with controlled alignment, the piezoelectric coupling can be disproportionately increased with respect to the dielectric constant which yields a g31 coefficient that can be enhanced more than seven times compared to the bulk piezoelectric material. Moreover, it is demonstrated that the use of high aspect ratio nanowires in the energy harvester resulted in significant improvement on the output electrical power of an energy harvester.
关键词： Energy harvesting,Nanowires,Finite element modeling (FEM),Voltage coefficient,Piezoelectric,The Mori-Tanaka method,Direct write,Nanocomposite
更新于2025-11-14 17:28:48
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Colloidal-Quantum-Dot-in-Perovskite Nanowires
摘要： Colloidal quantum dots are materials of interest in infrared detection – a consequence of their near-infrared light harvesting capability, tunable bandgap, and solution-processing. Herein we develop a quantum-dot-in-perovskite-nanowire consisting of PbS quantum dots embedded inside MAPbI3 nanowires. The kinetics of perovskite nanowire growth were tracked. We found that N, N-dimethylformamide induced the formation of perovskite nanowires, and that their growth was accelerated upon PbS quantum dot inclusion. We then used this nanocomposite to fabricate photodetectors that showed a light response from the visible to near infrared region up to 940 nm. Finally, a flexible photodetector was fabricated on a polyethylene terephthalate substrate.
关键词： MAPbI3 nanowires,flexible photodetector,PbS quantum dots
更新于2025-11-14 17:04:02
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Tunable optical and magnetic properties of Ni-doped CuSe nanowires using AAO template assisted hydraulic method
摘要： High uniformity of un-doped and Ni-doped CuSe nanowires have been fabricated through smelting the bulk and injecting the melted liquid into the anodic aluminum oxide (AAO) template. The Ni dopant concentration and morphology of CuSe nanowires can be well controlled via preparing the bulk materials and the channel size of AAO template. The cathodoluminescence (CL) peaks of the un-doped, 0.5 at% and 1.0 at% Ni-doped CuSe nanowires showed a redshift of about 26 nm and 42 nm from un-doped CuSe nanowires (579 nm), respectively. Furthermore, above room temperature ferromagnetism was observed in 1.0 at% Ni-doped CuSe nanowires at 300 K. The facile injection molding method fabricated nanowires with tunable optical and magnetic properties could be applied to prepare varied nanomaterials for spintronic devices in the further.
关键词： optical,anodic aluminum oxide (AAO),CuSe,doped,nanowires,magnetic
更新于2025-11-14 17:03:37