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La-doped p-type ZnO nanowire with enhanced piezoelectric performance for flexible nanogenerators
摘要： In recent years, energy harvesting has attracted considerable attention as a promising method to convert waste energy to useful energy. In particular, piezoelectric energy harvesters are of significant interest, because they have a simple structure and can be used to harvest energy regardless of weather or other environmental conditions. In accordance with the miniaturization trend of electronic devices driven by low power, piezoelectric nanogenerators (PENGs) using various nanostructured materials are being developed. Among them, ZnO nanowires (NWs) are most widely used for the use of PENGs. However, while research on n-type ZnO NWs is extensive, studies on p-type ZnO NWs are insufficient owing to their poor stability. In this study, La-doped p-type ZnO (La:ZnO) NWs were synthesized by a hydrothermal method to expand the applications of p-type ZnO and determine their potential as PENGs. XRD analysis showed that La3+ ions was well doped without the formation of any secondary phases and caused a change in the lattice parameter when compared to that of undoped ZnO. XPS analysis was performed to investigate the surface elemental compositions of La:ZnO NWs, and the morphology of La:ZnO NWs was investigated using SEM and TEM. We further studied the piezoelectric output performance of undoped and La-doped ZnO NWs, and found that La:ZnO NWs showed improved piezoelectric output performance as a result of electron screening effect of the p-type semiconductor.
关键词： p-type ZnO,La-doping,Flexible device,ZnO nanowires,Nanogenerators
更新于2025-09-23 15:23:52
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Influence of thermal oxidation temperature on the microstructure and photoelectrochemical properties of ZnO nanostructures fabricated on the zinc scraps
摘要： In this paper, zinc oxide (ZnO) nanowires were synthesized by thermal oxidation method of zinc scrap at various temperatures ranging between 400 °C and 900 °C under air atmosphere. The influence of different temperature on the phase structures, surface morphologies and photoelectrochemical (PEC) properties of ZnO nanowires were investigated. The characterizations were carried out via X-ray diffractometer (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The results showed that annealing temperature played a significant role on surface morphology and phase structure. The band gap energy of the ZnO nanowires changed between 3.12 and 3.194 eV. The photoelectrochemical (PEC) study of the ZnO nanowires was investigated in 0.1 M Na2SO4 aqueous solution. The PEC findings represented that the ZnO nanowire annealed at 600 °C had 252.2 mA/cm2 net photocurrent density which was the best efficiency and at least 10 times higher than that of the lowest one at 1.25 V (vs. VRHE). Mott-Schottky analysis showed that the ZnO nanowires behaved as n-type semiconductor. ZnO nanowire annealed at 600 °C had the highest carrier density value (Nd = 9.03 × 10^23). Moreover, the charge transfer behavior of the ZnO nanowires was determined by means of electrochemical impedance spectroscopy (EIS) measurements. As a result, this work recommends that the ZnO nanowires could be good candidate on PEC applications. Also, thermal oxidation method is an efficient method for fabrication of ZnO nanowires.
关键词： Thermal oxidation,Zn scrap,Electrochemical impedance spectroscopy (EIS),ZnO nanowires,Photoelectrochemical (PEC)
更新于2025-09-23 15:23:52
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A Low Frequency Vibration Energy Harvester Using ZnO Nanowires on Elastic Interdigitated Electrodes
摘要： This paper presents a low frequency piezoelectric vibration energy harvester using ZnO nanowires on elastic interdigitated electrodes. The interdigitated electrodes are formed using electroplated Ni and have suspended parts at the edges that are elastic and deformable by applying external force. A spherical Ni ball is used as a proof mass, which transforms a low frequency mechanical vibration into the force applied to deform the elastic electrodes. The ZnO nanowires are grown selectively on the electrodes and can generate a piezoelectric potential when the elastic electrodes are deformed by the proof mass activated by the external mechanical vibration. The proposed operation concept is demonstrated using two different types of energy harvesters, which have simple suspended part and cantilever array structures added to the electrodes, respectively. The output voltage of the fabricated harvesters is measured using a vibration exciter at 6 Hz sinusoidal vibration with an acceleration of 0.5 g. Maximum output power of 12.8 pW and 18.8 pW was generated with a load resistance of 1 MΩ for the harvesters using the simple suspended structure and cantilever array, respectively.
关键词： Spherical Proof Mass,Elastic Interdigitated Electrodes,ZnO Nanowires,Low Frequency Piezoelectric Vibration Energy Harvester
更新于2025-09-23 15:23:52
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Single-Crystal ZnO/AlN Core/Shell Nanowires for Ultraviolet Emission and Dual-Color Ultraviolet Photodetection
摘要： Core–shell nanostructures can combine the advantages of different functional materials to realize property tunability and enhance optical and optoelectrical performance. Here, vertically aligned ZnO/AlN core/shell nanowires have been facilely fabricated by sputtering AlN layer onto the ZnO nanowires grown by vapor phase transport. The morphological and structural characterization reveals that single-crystal AlN shell layer with thickness of ≈15 nm is coated uniformly on the single-crystal ZnO nanowire with diameters of ≈330 nm. The core/shell nanowire exhibits 24 times enhancement of ultraviolet emission and quenching of the deep level emission from ZnO. Moreover, under ultraviolet irradiation (325 nm), the photodetector based on the core/shell nanowire displays higher photoresponsivity (from 3.8 × 103 to 2.05 × 104 A W?1), faster response speed (from 397 to 28 ms), and higher I325nm/Idark ratio (from 453 to 1.1 × 104) than that bare ZnO nanowire device. Under the vacuum ultraviolet (193 nm) illumination, the I193nm/Idark ratio and photoresponsivity are 300 and 381 A W?1, respectively. In one word, this paper employs a facile and general technique to solve a challenging fabrication issue, and obtains perfect crystal core/shell structure with high performance for ultraviolet emission and detection.
关键词： single-crystal core/shell,AlN,ZnO nanowires,ultraviolet emission,dual-color ultraviolet photodetection
更新于2025-09-23 15:23:52
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Polar surface dominated octagonal Sn doped ZnO nanowires and their room-temperature photoluminance properties
摘要： Polar surface dominated Sn doped ZnO nanowires (NWs) with an octagonal shaped cross section have been fabricated by chemical vapor deposition method. The NWs grew along [01 0] direction, and were wrapped by non-polar surface (2 0) and polar surfaces (0001) and (1 1). Planar defects in (0001) plane were formed in the middle of the doped NWs, and strain concentration occurred around the planar defects, which might lower the energy in the wurtzite lattice and thus maintain polar surface dominated configuration. X-ray photoelectron spectroscopy (XPS) and Raman tests reveal that the concentration of Oxygen vacancy (VO) was significantly lowered after doping, which led to the reduced deep level emission (DLE).
关键词： Polar surface,Photoluminance,Sn-doped ZnO Nanowires,Microstructure
更新于2025-09-23 15:23:52
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Enhancement of multi-photon Raman scattering and photoluminescence emission from Li-doped ZnO nanowires
摘要： Uniform Li-doped ZnO nanowires have been fabricated by thermal evaporation method. The ZnO formation and the Li incorporation have been discussed and the formation path of preparation products has also been explained in terms of the stability of Zn and Li vapor in an aerobic atmosphere. The strongest vibration mode at 437.2 cm?1 in the multi-photon Raman scattering of the as-prepared products at room temperature indicates that the Li-doped ZnO nanowires still keep the hexagonal (wurtzite) structure. Raman spectra of Li-doped ZnO with different doping concentrations confirm that the variation of Raman peaks in the range of 550 cm?1～650 cm?1 is caused by the doping of lithium. The photoluminescence property at room temperature shows a blue-shift compared with undoped ZnO in the ultraviolet region. The Gauss fitting analyzed results indicate that the broad-band is composed of one green luminescence (GL) band, one yellow luminescence (YL) band, and one red luminescence (RL) band, respectively. The GL (2.447 eV) could be attributed to the singly ionized oxygen vacancies. The origin of the YL (2.245 eV) could be assigned to the transition of an electron from the conduction band (or a shallow donor) to the Li acceptor level. The RL (1.977 eV) could be assigned to the transitions between a shallow donor (at low temperature) or the conduction band (at higher temperature). Furthermore, the luminescence spectra at low temperature confirm the increase of defect levels like oxygen vacancies.
关键词： li-doped ZnO nanowires,formation process,photoluminescence,multi-photon raman scattering
更新于2025-09-23 15:23:52
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Surface doping of ZnO nanowires with Bi: Density-functional supercell calculations of defect energetics
摘要： Defect calculations using the density and hybrid functionals in combination with the supercell approach are employed to characterize the electrical properties of a number of ZnO nanowires of various thicknesses doped with Bi atoms occupying surface sites. The variation of the differences between the total energies of charged and neutral supercells with the supercell size is studied, which led the authors to devise an extrapolation procedure to obtain reliable defect energetics in the dilute defect limit. The calculated defect formation energies indicate that although the substitution of Bi into Zn or O sites can take place spontaneously under suitable thermodynamic conditions, the substitution into Zn sites is generally more likely. The defect (charge-state) transition energies are computed and parameterized as a function of the nanowire thickness. It is revealed that the substitution of Bi into O (Zn) sites on the surface of ZnO nanowires yields deep acceptor (shallow donor) levels (except for extremely thin nanowires). It is therefore concluded that the incorporation of Bi into the surface of ZnO nanowires results in n-type doping.
关键词： ZnO nanowires,defect energetics,n-type doping,bismuth doping,supercell calculations,density functional theory
更新于2025-09-23 15:23:52
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Enhanced Ultraviolet Emission from Hydrothermally Grown ZnO Nano-Grass on Si Substrate
摘要： Highly crystalline one-dimensional zinc oxide (ZnO) nano-grass was grown on silicon (Si) substrate by a modified hydrothermal method. A predominantly c-oriented ZnO nano-grass with an average diameter of 40–60 nm and length of 1.5–2.0 lm was obtained. From the photoluminescence (PL) measurement, we observed a defect-free, intense ultraviolet emission of as-grown ZnO nano-grass, confirming the absence of singly ionized oxygen vacancies. The absence of green deep-level emission in the PL spectrum further implies a high crystallinity of as-grown ZnO nano-grass. The high-quality ZnO nano-grass has potential applications in single nanowire-based light-emitting diodes, solar cells, themoresistive sensing, photocatalysis, ultraviolet photodetectors, optical switches, waveguides and nano-lasers.
关键词： photoluminescence,ZnO nanowires,annealing process,ultraviolet emission,hydrothermal method
更新于2025-09-23 15:22:29
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Field emission from Au nanoparticles decorated ZnO nanowires
摘要： ZnO nanowires with Au nanoparticle decoration were prepared. Photoluminescence results reveal quenching of both the band edge and visible emissions of ZnO nanowires after the Au nanoparticle decoration. The field emission properties fro\ Au nanoparticles decorated ZnO nanowires were measured and increasing turn-on fields were observed. The observed phenomena were attributed to electron transport between ZnO and Au nanoparticle.
关键词： ZnO nanowires,Au nanopartical,field-emisison,electron transport
更新于2025-09-23 15:21:21
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[IEEE 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) - Berlin, Germany (2019.6.23-2019.6.27)] 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) - In-Situ Transmission Electron Microscopy Coupled with Resonant Microcantilever for Comprehensive Evaluating Sulfurization Performance of Zinc Oxide Nanowires
摘要： This paper reports a new technique with in-situ transmission electron microscopy (in-situ TEM) and resonant microcantilever to comprehensively evaluate sulfurization performance of ZnO nanowires. Herein, in-situ TEM is used to real-time observe the sulfurization process of ZnO nanowires under SO2-contained atmosphere. temperature-varying micro-gravimetric method, thermodynamic interaction between ZnO nanowires and SO2 molecules is quantitatively evaluated by resonant microcantilever. By exposing the ZnO nanowires sample to SO2-contained atmosphere, a thick shell layer of ZnSO3 can be formed onto the surface of ZnO nanowires and a novel core-shell nanowire structure of ZnO@ZnSO3 is obtained finally. According to our comprehensive evaluation results, the ZnO nanowires sample with 100 nm diameter exhibits high reactive to SO2 molecules and is suitable for SO2 capture and storage.
关键词： sulfurization process,ZnO nanowires,thermodynamic parameter extraction,In-situ TEM
更新于2025-09-23 15:19:57