Electrically Addressable Hybrid Architectures of Zinc Oxide Nanowires Grown on Aligned Carbon Nanotubes

The fabrication and characterization of hybrid architectures of ZnO nanowires (ZNWs) grown on organized carbon nanotubes (CNTs), by a two‐step chemical vapor deposition (CVD) process involving CNT growth from a hydrocarbon source followed by ZNW growth using a Zn metal source, is reported. The ZNWs grow uniformly and radially from individual CNTs and CNT bundles, and the aligned morphology of the CNTs is not disturbed by the ZNW growth process. The nucleation and growth of ZnO crystals on CNTs are analyzed in relation to the classical vapor–solid mechanism. Importantly, the CNTs make uniform and distributed electrical contact to the ZNWs, with up to a 1000‐fold yield advantage over conventional ZNW growth on a flat substrate. Hybrid ZNW/CNT sheets are fabricated by scalable CVD, rolling, and printing methods; and their electrical properties, which are governed by transport through the anisotropic CNT network, are characterized. Functional interaction between the ZNWs and CNTs is demonstrated by photoconductive behavior and photocurrent generation of the hybrid material under UV illumination. There is significant future opportunity to extend these processing methods to fabricate other functional oxides on CNTs, and to build devices that harness the attractive properties of ZNWs and CNTs with high volumetric efficiency over large areas.     

Characterization and Field‐Emission Properties of Needle‐like Zinc Oxide Nanowires Grown Vertically on Conductive Zinc Oxide Films

Needle‐like ZnO nanowires with high density are grown uniformly and vertically over an entire Ga‐doped conductive ZnO film at 550 °C. The nanowires are grown preferentially in the c‐axis direction. The X‐ray diffraction (XRD) θ‐scan curve shows a full width at half maximum (FWHM) value of 2°. This indicates that the c‐axes of the nanorods are along the normal direction of the substrate surface. The investigation using high‐resolution transmission electron microscopy (HRTEM) confirmed that each nanowire is a single crystal. A room‐temperature photoluminescence (PL) spectrum of the wires consists of a strong and sharp UV emission band at 380 nm and a weak and broad green–yellow band. It reveals a low concentration of oxygen vacancies in the ZnO nanowires and their high optical quality. Field electron emission from the wires was also investigated. The turn‐on field for the ZnO nanowires was found to be about 18 V μm^–1 at a current density of 0.01 μA cm^–2. The emission current density from the ZnO nanowires reached 0.1 mA cm^–2 at a bias field of 24 V μm^–1.     

Intrinsic and Doped Zinc Oxide Nanowires for Transparent Electrode Fabrication via Low-Temperature Solution Synthesis

Undoped and doped zinc oxide (ZnO) nanowires were synthesized by decomposing metal salts in trioctylamine at 300°C. By adding metal salts during the formation of the wires, effective incorporation of Ga and Al up to 5% was achieved, as measured by energy-dispersive x-ray spectroscopy and Auger electron spectroscopy. No secondary phase was detected by high-resolution transmission electron microscopy and x-ray diffraction. The nanowires were single-crystalline with a wurtzite lattice structure. Films made with doped wires show a complex dependence of the sheet resistance on processing conditions and dopant concentration. Thermal annealing treatment reduced the sheet resistance to values of 10³ Ω/square.     

In Situ Damage Detection for Fiber‐Reinforced Composites Using Integrated Zinc Oxide Nanowires

A multifunction material that increases strength is capable of harvesting energy from ambient vibration and acts as a structural health monitoring system is presented. Current in situ damage detection of fiber‐reinforced composites typically uses methods which require external sensors, precise initial measurements for each component under evaluation, or input current to the structure. To overcome these limitations, this work utilizes a multifunctional interphase of piezoelectric zinc oxide nanowires integrated into fiber‐reinforced composites to provide an in situ ability to sense damage. The nanowires are grown onto insulating reinforcing fibers which are sandwiched between carbon fiber electrodes, thus fully integrating the sensing element into the fiber‐reinforced composite. The fully distributed nanowire interphase proves capable of detecting multiple damage modes using passive voltage measurements as demonstrated during multiple loading configurations. This work also analyzes voltage emissions corresponding to damage to provide signal characteristics corresponding to the damage state of the specimen to indicate damage progression and the approach of catastrophic failure. The result of this work is thus a multifunctional structural material with damage detection capabilities. The principles investigated in this work can also be extended to alternative structural composites containing integrated piezoelectric materials in the form of nanoparticles, nanowires, or films.     

氧化锡纳米线的光致发光性能分析

通过热蒸发沉积法在常压、900°C高温条件下,合成了氧化锡纳米线结构。利用扫描电子显微镜、透射电子显微镜及选区电子衍射对样品的表面形貌和微结构进行了表征,X射线衍射、傅里叶变换红外光谱进一步证明所制纳米结构为金红石型氧化锡单晶结构。在77K和300K温度条件下,研究了所制氧化锡纳米线及其在氧气气氛中退火后的光致发光性能。     

Ga contamination in silicon by Focused Ion Beam milling: Dynamic model simulation and Atom Probe Tomography experiment

Focused Ion Beam (FIB) milling is a widely used and important technique to prepare Transmission Electron Microscopy (TEM) lamella samples. However, it unavoidably introduces contamination in the samples like implanted ions. While the conventional ion-solid simulation model, Binary Collision Approximation (BCA), is unable to describe the FIB process, a dynamic BCA model is used in this study to predict the level of Ga implantation along the substrate depth. The FIB process involves significant material transport and local composition alteration, which requires a dynamic model for simulation. To validate the dynamic BCA model's application on simulating the FIB process, atomic level composition analysis Atom Probe Tomography (APT) is performed on Ga FIB processed silicon samples. The experimental data confirm that the dynamic BCA model is capable to predict FIB induced Ga ion implantation in silicon samples.     

From Layered Basic Zinc Acetate Nanobelts to Hierarchical Zinc Oxide Nanostructures and Porous Zinc Oxide Nanobelts

Novel hierarchical ZnO nanostructures, porous ZnO nanobelts, and nanoparticle chains are prepared from a precursor of synthetic bilayered basic zinc acetate (BLBZA) nanobelts. BLBZA nanobelts are obtained by a simple synthetic route under mild conditions. X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, infrared spectroscopy, and thermal analysis are used to characterize the BLBZA nanobelts and ZnO nanostructures. The obtained BLBZA precursor consists of a lamellar structure with two interlayer distances of 1.33 and 2.03 nm, exhibits a beltlike morphology, and has widths of 200 to 600 nm, thicknesses of 10 to 50 nm, and lengths of up to 50 μm. Refluxing an aqueous dispersion of BLBZA nanobelts at 120 °C for 12 h leads to the formation of well‐defined hierarchical ZnO nanostructures. The time‐dependent shape‐evolution process suggests that spindlelike ZnO particles form first, and then the ringlike nanosheets grow heterogeneously on the backbone of these spindles. In addition, calcination in air can remove ligand molecules and intercalated water molecules from BLBZA nanobelts, resulting in the formation of porous ZnO nanobelts and nanoparticle chains. The BLBZA nanobelts serve as templates during the transformation to form ZnO beltlike nanoparticle chains without morphological deformation. Photoluminescence results show that both the as‐synthesized hierarchical ZnO nanostructures and porous ZnO nanobelts show a narrow and sharp UV emission at 390 nm and a broad blue–green emission at above 466 nm when excited by UV light.     

Field-Emission Performance of Wormhole-Like Mesoporous Tungsten Oxide Nanowires

We prepared wormhole-like mesoporous tungsten oxide nanowires on a Cu-tape/Si substrate, and explored the field-emission performances. The wormhole-like mesoporous tungsten oxide nanowires of 20 nm diameter exhibited excellent field-emission properties with extremely low turn-on and threshold fields (emission current density of 10 μA/cm² and 10 mA/cm²) of 0.083 V/μm and 1.75 V/μm, respectively, as well as current stability of about 1400 μA/cm² at a fixed field of 0.67 V/μm. This approach provides an efficient methodology for fabricating a field emitter that is expected to work at low voltage and can be used in field-emission displays.     

Thermally Stable Silver Nanowire–Polyimide Transparent Electrode Based on Atomic Layer Deposition of Zinc Oxide on Silver Nanowires

The performance of a flexible transparent conductive electrode with extremely smooth topography capable of withstanding thermal processing at 300 °C for at least 6 h with little change in sheet resistance and optical clarity is reported. In depth investigation is performed on atomic layer deposition (ALD) deposited ZnO on Ag nanowires (NWs) with regard to thermal and atmospheric corrosion stability. The ZnO coated nanowire networks are embedded within the surface of a polyimide matrix, and the <2 nm roughness freestanding ­electrode is used to fabricate a white polymer light emitting diode (PLED). PLEDs obtained using the ZnO‐AgNW‐polyimide substrate exhibit comparable performance to indium tin oxide (ITO)/glass based devices, verifying its efficacy for use in optoelectronic devices requiring high processing temperatures.     

Zinc Oxide Nanoparticles with Defects

Zinc oxide in the form of nanoscale materials can be regarded as one of the most important semiconductor oxides at present. However, the question of how chemical defects influence the properties of nanoscale zinc oxide materials has seldom been addressed. In this paper, we report on the introduction of defects into nanoscale ZnO, their comprehensive analysis using a combination of techniques (powder X‐ray diffraction (PXRD), X‐ray absorption spectroscopy/extended X‐ray absorption fine structure (XAS/EXAFS), electron paramagnetic resonance (EPR), magic‐angle spinning nuclear magnetic resonance (MAS‐NMR), Fourier‐transform infrared (FTIR), UV‐vis, and photoluminescence (PL) spectroscopies coupled with ab‐initio calculations), and the investigation of correlations between the different types of defects. It is seen that defect‐rich zinc oxide can be obtained under kinetically controlled conditions of ZnO formation. This is realized by the thermolysis of molecular, organometallic precursors in which ZnO is pre‐organized on a molecular scale. It is seen that these precursors form ZnO at low temperatures far from thermodynamic equilibrium. The resulting nanocrystalline ZnO is rich in defects. Depending on conditions, ZnO of high microstructural strain, high content of oxygen vacancies, and particular content of heteroatom impurities can be obtained. It is shown how the mentioned defects influence the electronic properties of the semiconductor nanoparticles.     

High-Performance Chemical-Bath-Deposited Zinc Oxide Thin-Film Transistors

Solution-processed transparent zinc oxide (ZnO) transistors are demonstrated using a chemical bath deposition process for ZnO deposition. The process is glass compatible and amenable to producing fully transparent electronics. Mobility as high as 3.5 cm²/V ldr s with on-off ratios of ~10⁵ is realized. The transparency of ZnO allows for complete coverage of the pixel by the pixel drive transistors; analysis shows that the performance achieved herein is sufficient even to drive high-brightness organic light-emitting diode (OLED) displays by exploiting the high mobility and optical transparency of these devices. This makes this technology extremely attractive for use in active-matrix OLED display applications.     

Surface Wettability of Nanostructured Zinc Oxide Films

Zinc oxide (ZnO) nanograin and nanorod films were prepared by magnetron sputter deposition and an aqueous solution growth method. Their surface wettability was studied in relation to their surface morphologies. While the surfaces of both films were hydrophobic, the nanorod films exhibited higher surface hydrophobicity. A superhydrophobic surface was obtained on a ZnO nanorod film with a water contact angle of 151 deg. Results have shown that their surface wettability was influenced by the morphology of ZnO nanostructures, including the grain size, the length, and density of nanorods. Both types of ZnO films showed switchable wettability under ultraviolet irradiation and dark storage.     

氧化锌纳米颗粒缺陷能级发光特性研究

报道了在室温下用荧光光谱仪和飞秒脉冲激光激发诱导光致发光．获得氧化锌纳米颗粒(平均直径约为10nm)缺陷发光光谱的实验，验证了氧化锌纳米颗粒缺陷能级的位置。锌填隙缺陷在距离导带底0．4eV处产生浅施主能级．锌空位缺陷在价带顶0．3eV处产生浅受主能级，氧锌替位缺陷在价带顶1．08eV处产生深受主能级，在导带底1．56eV处有氧空位缺陷引起的深杂质能级产生．氧填隙缺陷在价带顶1．35eV处产生深受主能级。     

Cu掺杂氧化锌氧化物的热学性能

基于线性响应的密度泛函微扰理论研究了Cu掺杂纤锌矿结构氧化物ZnO的热学参数和热学性能。结果表明,Cu掺杂导致ZnO氧化物晶胞减小;在计算温度区间,纯的ZnO和Cu掺杂的ZnO的晶格热容均随温度升高不断增大,Cu掺杂的ZnO具有较高的晶格热容;纯的ZnO和Cu掺杂ZnO的晶格热容在最高温度900K时分别达到69.1J·(mol-1·K-1)和152.8J·(mol-1·K-1)。纯的ZnO和Cu掺杂ZnO的德拜温度均随温度升高而不断增大;在175K以下,Cu掺杂ZnO体系的德拜温度高于未掺杂体系,在175K以上,Cu掺杂ZnO体系的德拜温度低于未掺杂体系。Cu掺杂在ZnO中引入了新的振动模式。Cu掺杂ZnO氧化物应具有较高的晶格热导率。     

Structure and Morphology of Zinc Oxide Nanorods

The properties of nanorods made of high-energy-gap Zn _x Mg_{1 – x}O semiconductors are experimentally investigated using the new system of 3D manipulation of individual nanospecimens. The technology used to prepare Zn _x Mg_{1 – x}O nanorods via gas-phase deposition on a substrate, the process whereby individual nanorods are selected by means of nanocomposite tweezers with the shape-memory effect in the vacuum chamber of a two-beam scanning microscope, and the results obtained when their structure and morphology are experimentally studied using transmission electron spectroscopy are described. The prospects that nanophotonic, nanosensorial, and nanoelectronic devices can be fabricated from Zn _x Mg_{1 – x}O nanorods via the new nanomanipulation technique are discussed.     

Magnesium Oxide Nanowires Synthesized at Low Temperature by Vapor-liquid-solid Mechanism

Magnesium oxide(MgO) nanowires were synthesized on the gold-coated Si(100) and MgO(100) substrates at lower temperature(600℃) by pulsed liquid injection metal organic chemical vapor deposition(MOCVD). The gold catalyst could be found on the tips of nanowires, which presents the vapor-liquid-solid(VLS) growth mechanism. Reactive species(oxygen or magnesium) have strong effects on the growth of nanowires. Abundant reactive species kill the vertically aligned nanowires to be randomly aligned ones or even chan...     

虚拟式氧化锌避雷器在线检测系统

讨论了氧化锌避雷器性能参数的检测方法,提出了虚拟式氧化锌避雷器性能参数的在线测量方案及系统组成,对测量数据进行了分析与处理.虚拟式检测系统具有体积小、重量轻、数据处理方便等优点,是电力系统避雷器在线检测的新的方法.     

Carbon-Incorporated Amorphous Indium Zinc Oxide Thin-Film Transistors

We propose the use of amorphous-carbon indium zinc oxide (a-CIZO) as a channel material for thin-film transistor (TFT) fabrication. This study chose a carbon dopant as a carrier suppressor and strong oxygen binder in amorphous-indium zinc oxide (a-IZO) channel material. a-CIZO thin films were deposited using radiofrequency (RF) sputtering and postannealed at 150°C. X-ray diffraction and transmission electron microscopy analysis revealed that the film remained amorphous even after postannealing. The a-CIZO TFT postannealed at 150°C exhibited saturation field-effect mobility of 16.5 cm² V^?1 s^?1 and on–off current ratio of ～4.3 × 10⁷.     

Zinc Oxide Nanorods Grown by Arc Discharge

The arc discharge method was employed to fabricate zinc oxide (ZnO) nanorods with wurtzite structure. The microstructure analysis by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) demonstrated that the ZnO nanorods grew along the [0001] direction. On average, the diameter and length of the nanorods were about 40 nm (some are as thin as 5 nm) and several hundred nanometers, respectively. The photoluminescence (PL) of the nanorods showed an ultraviolet band, a violet band, and a green band. The PL mechanism was discussed with the growth process and Raman spectroscopy.