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1.
ZnO nanowire arrays have been successfully synthesized on transparent quartz glass substrate by chemical vapor deposition technique. Our work demonstrates the critical role of the growth temperature and the buffer layer on the effective control of the morphology of ZnO nanowires. A proper growth temperature and the thicker buffer layer could promise the good alignment and high density of the nanowires. The room-temperature photoluminescence spectrum shows that the buffer layer has also great effects on optical properties of ZnO nanowire arrays. The integrated intensity ratio [IUV/IVisible band] of the ZnO UV emission peak to visible band emission decreases with the increase of the thickness of the buffer layers. The obtained nanowire arrays have transmittance of above 50% in the visible region. 相似文献
2.
Clotaire Chevalier-César Martine Capochichi-Gnambodoe Yamin Leprince-Wang 《Applied Physics A: Materials Science & Processing》2014,115(3):953-960
Well-controlled ZnO nanowire arrays have been synthesized using the hydrothermal method, a low temperature and low cost synthesis method. The process consists of two steps: the ZnO buffer layer deposition on the substrate by spin-coating and the growth of the ZnO nanowire array on the seed layer. We demonstrated that the microstructure and the morphology of the ZnO nanowire arrays can be significantly influenced by the main parameters of the hydrothermal method, such as pH value of the aqueous solution, growth time, and solution temperature during the ZnO nanowire growth. Scanning electron microscopy observations showed that the well oriented and homogeneous ZnO nanowire arrays can be obtained with the optimized synthesis parameters. Both x-ray diffraction spectra and high-resolution transmission electron microscopy (HRTEM) observations revealed a preferred orientation of ZnO nanowires toward the c-axis of the hexagonal Wurtzite structure, and HRTEM images also showed an excellent monocrystallinity of the as-grown ZnO nanowires. For a deposition temperature of 90 °C, two growth stages have been identified during the growth process with the rates of 10 and 3 nm/min, respectively, at the beginning and the end of the nanowire growth. The ZnO nanowires obtained with the optimized growth parameters owning a high aspect ratio about 20. We noticed that the starting temperature of seed layer can seriously influence the nanowire growth morphology; two possible growth mechanisms have been proposed for the seed layer dipped in the solution at room temperature and at a high temperature, respectively. 相似文献
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Large area, well-aligned type-II ZnO/ZnTe core-shell nanowire arrays have been fabricated on an a-plane sapphire substrate. The ZnO nanowires were grown in a furnace by chemical vapor deposition with gold as catalyst and then were coated with a ZnTe shell on the ZnO nanowires surface by a metal-organic chemical deposition chamber. The morphology and size distribution of the ZnO/ZnTe core-shell nanowire arrays were studied by scanning electron microscopy (SEM) and the crystal structure was examined by x-ray diffraction (XRD). Transmission measurement was used to study the optical properties of the core-shell nanowires. The results indicated that the ZnO/ZnTe core-shell nanowire arrays have good crystalline quality. In addition, it was found that the nanowire arrays have good light absorption characteristics and these properties make it suitable for making photovoltaic devices. 相似文献
5.
Liang-Wen Ji Shi-Ming Peng Wei-Shun Shih I-Tseng Tang 《Journal of Physics and Chemistry of Solids》2009,70(10):1359-2454
We demonstrate that vertical well-aligned crystalline ZnO nanowire arrays were grown on ZnO/glass substrates by a low-temperature solution method. Different thicknesses of ZnO seed layers on glass substrates were prepared by radio-frequency sputtering. In this work it was found that the morphology of ZnO nanowires strongly depends on the thickness of ZnO seed layers. The average diameter of nanowires is increased from 50 to 130 nm and the nanowire density is decreased from 110 to 60 μm−2 while the seed layer thickness is varied from 20 to 1000 nm. The improved control of the morphology of ZnO nanowire arrays may lead to an enhanced carrier collection of hybrid polymer photovoltaic devices based on ZnO. 相似文献
6.
R.Q. Guo J. Nishimura M. Matsumoto M. Higashihata D. Nakamura J. Suehiro T. Okada 《Applied physics. B, Lasers and optics》2008,90(3-4):539-542
Ordered ZnO nanowire arrays have been fabricated in N2 background gas by catalyst-free nanoparticle-assisted pulsed-laser deposition. A single ZnO nanowire was collected in an
electrode gap by dielectrophoresis. Under the optical pumping above an exciting laser (λ= 355 nm) threshold of ∼ 334 kW/cm2, ultraviolet lasing action in a single ZnO nanowire was observed at room temperature, indicating that the as-synthesized
nanowires in pure N2 background gas are of high quality. The crystalline facets of both ends of the nanowire acted to form an optical cavity.
Therefore, the mode spacings corresponding to cavity lengths of the respective nanowires were observed in photoluminescence
spectra.
PACS 78.66.Hf; 81.07.Bc; 78.67.-n; 81.16.Mk 相似文献
7.
用一种低成本的方法制备出了树形结构Si/ZnO纳米线阵列。首先在室温条件下用金属辅助化学腐蚀法在Si(100)衬底上制备了Si纳米线阵列,Si纳米线的直径尺寸及分布都很均匀,通过改变腐蚀时间,能够得到高度不同的Si纳米线阵列。利用磁控溅射在Si纳米线表面制备一层ZnO薄膜,然后利用水热法在Si纳米线阵列上生长了ZnO纳米线。通过扫描电子显微镜(SEM)、能谱分析仪(EDS)和光致发光(PL)测试对样品进行了表征。通过这种方法制备的Si/ZnO复合结构在太阳能电池、光催化等领域有潜在应用价值。 相似文献
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用水热法在ZnO薄膜上制备了直径、密度及取向可控的ZnO纳米线阵列。ZnO薄膜是通过原子层沉积(ALD)方法制备并在不同温度下退火处理得到的,退火温度对ZnO薄膜的晶粒尺寸、结晶质量和缺陷性质有很大的影响。而ZnO薄膜的性质对随后生长的ZnO纳米线的直径、密度及取向能起到调节控制的作用。通过扫描电子显微镜(SEM)、X射线衍射(XRD)仪和光致发光(PL)测试对ZnO薄膜和ZnO纳米线进行了表征。最后得到的垂直取向的ZnO纳米线阵列适合在发光二极管和太阳能电池等领域使用。 相似文献
10.
Xianghui Zhang Luying Li Jun Su Yumei Wang Yuling Shi Xiaoliang Ren Nishuang Liu Aiqing Zhang Jun Zhou Yihua Gao 《Laser \u0026amp; Photonics Reviews》2014,8(3):429-435
Wavelength‐tunable light‐emitting diodes (LEDs) of GaxZn1–xO nanowire arrays are demonstrated by a simple modified chemical vapor deposition heteroepitaxial growth on p‐GaN substrate. As a gallium atom has similar electronegativity and ion radius to a zinc atom, high‐level Ga‐doped GaxZn1–xO nanowire arrays have been fabricated. As the x value gradually increases from 0 to 0.66, the near‐band‐edge emission peak of GaxZn1–xO nanowires shows a significant shift from 378 nm (3.28 eV) to 418 nm (2.96 eV) in room‐temperature photoluminescence (PL) measurement. Importantly, the electroluminescence (EL) emission of GaxZn1–xO nanowire arrays LED continuously shifts with a wider range (∼100 nm), from the ultraviolet (382 nm) to the visible (480 nm) spectral region. The presented work demonstrates the possibility of bandgap engineering of low‐dimensional ZnO nanowires by gallium doping and the potential application for wavelength‐tunable LEDs. 相似文献
11.
Co100?xSnx alloy nanowires were fabricated by electrodeposition of Co2+ and Sn2+ into anodic aluminum oxide (AAO) templates. X-ray diffraction results indicate that the crystal structures of the nanowires changed from polycrystal to amorphism, and then to polycrystal again with the increase of Sn content in the nanowires. Transmission electron microscopy result shows that the nanowires are about 50 nm in diameter and the aspect ratio is approximately 75. The magnetic response of the arrays was measured using vibrating sample magnetometry at room temperature. The results show that the coercivity and squareness with the magnetic field along the nanowire arrays decrease with the increase of the Sn content. Nanowires exhibit obviously uniaxial magnetic anisotropy, and the easy magnetizing axis is parallel to the nanowires owing to the large shape anisotropy. 相似文献
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用SnO和Zn的均匀混合物在高温下共烧通过VLS机制制备出孪晶ZnO纳米线的均匀结构。SEM图像显示孪晶ZnO纳米线的直径在100~200nm之间,长度在几十微米到几百微米之间的范围内,有的甚至达到了毫米级,产率也非常的高。TEM图像中ZnO孪晶纳米线顶端的金属Sn颗粒表明了孪晶结构的Sn催化生长。高分辨电子图谱显示了氧化锌纳米线孪晶结构的特征。电子衍射分析发现孪晶氧化锌的晶带轴的方向是[0110],孪晶面为(1013),并且通过明场像和暗场像分析了孪晶纳米线的晶格关系,确定了孪晶纳米线的汽-液-固(VLS)生长机制。 相似文献
13.
We report patterned horizontal growth of ZnO nanowires on SiO2 surface for the study of electrical and luminescent characteristics of individual nanowires and for device applications. Patterns of gold catalytic seed islands with barrier layers which suppress vertical growth were employed to facilitate horizontal growth on SiO2 surface. After the growth, ZnO nanowire devices are fabricated by patterning electrodes aligned over the seed islands and their device characteristics are investigated. We could also investigate history of synthesis conditions by obtaining local luminescence characteristics along individual nanowires. 相似文献
14.
A. Rahm M. Lorenz T. Nobis G. Zimmermann M. Grundmann B. Fuhrmann F. Syrowatka 《Applied Physics A: Materials Science & Processing》2007,88(1):31-34
We report on the high-pressure pulsed-laser deposition growth of periodic arrays of free-standing single zinc oxide nanowires
with uniform hexagonal arrangement and cross-section with thickness of less than 100 nm. In order to achieve the wire alignment,
we prepared an ordered array of catalytic gold seed particles by a nanosphere lithography mask transfer technique using monodisperse
spherical polystyrol nanoparticles. These templates were investigated by scanning electron microscopy and atomic force microscopy
prior to nanowire growth. X-ray diffraction revealed the epitaxial relationships between the nanostructures and the a-plane
sapphire substrate and excellent crystal quality. The optical properties of the ZnO nanowire arrays were measured by cathodoluminescence.
PACS 61.82.Rx; 81.05.-t; 81.05.Dz; 81.10.-h 相似文献
15.
Changyong LanJiangfeng Gong Yun SuKenan Li Shaoguang Yang 《Physica E: Low-dimensional Systems and Nanostructures》2012,44(4):791-796
SnO2/ZnO hierarchical nanostructures were synthesized by a two-step carbon assisted thermal evaporation method. SnO2 nanowires were synthesized in the first step and were then used as substrates for the following growth of ZnO nanowires in the second step. Sn metal droplets were formed at the surfaces of the SnO2 nanowires during the second step and were acted as catalyst to facilitate the growth of ZnO nanowires via vapor-liquid-solid mechanism. Room temperature photoluminescence measurements showed that the SnO2/ZnO hierarchical nanostructures exhibited a strong green emission centered at about 520 nm and a weak emission centered at about 380 nm. The emissions from the SnO2 were drastically constrained due to screen effect caused by the ZnO layer. 相似文献
16.
Sang Sub Kim Sun-Woo Choi Han Gil Na Dong Sub Kwak Yong Jung Kwon Hyoun Woo Kim 《Current Applied Physics》2013,13(3):526-532
ZnO–SnO2 branch–stem nanostructures were realized on a basis of a two-step process. In step 1, SnO2-stem nanowires were synthesized. In step 2, ZnO-branch nanowires were successfully grown on the SnO2-stem nanowires through a simple evaporation technique. We have pre-deposited thin Au layers on the surface of SnO2 nanowire stems and subsequently evaporated Zn powders on the nanowires. The ZnO branches, which sprouted from the SnO2 stems, had diameters in a range of 30–35 nm. As-synthesized branches were of single crystalline hexagonal ZnO structures. Since the branch tips were comprised of Au-containing nanoparticles, the Au-catalyzed vapor–liquid–solid growth mechanism was more likely to control the growth process of the ZnO branches. To test a potential use of ZnO–SnO2 branch–stem nanostructures in chemical gas sensors, their sensing performances with respect to NO2 gas were investigated, showing the promising potential in chemical gas sensors. 相似文献
17.
Vertically aligned one-dimensional ZnO nanowire arrays have been synthesized by a hydrothermal method on sol–gel derived ZnO films. Sol–gel derived ZnO films and corresponding ZnO nanowire arrays have been characterized by X-ray diffraction and field-emission scanning electron microscopy. The effect of sol–gel derived ZnO film surface on the morphology of ZnO nanowire arrays has been investigated. The authors suggest from our investigation that sol–gel derived ZnO films affect the growth of one-dimensional ZnO nanostructures. Not only crystalline ZnO films but also amorphous ones can act as a scaffold for ZnO nucleus. Tilted ZnO micro-rods are grown on ZnO gel films, whereas vertically aligned ZnO nanowire arrays are grown on nanometer-sized ZnO grains. The average diameter of ZnO nanowire arrays are correlated strongly with the grain size of sol–gel derived ZnO films. 相似文献
18.
综合氧化锌纳米线(ZnO NWs)的光学活性与聚苯胺(PANI)的空穴传输特性,设计并制备了一种聚合物/ZnO纳米线电致发光材料,并对其发光特性进行了研究。通过高分子络合软模板法,将有序的单晶ZnO NWs均匀生长在覆有铟锡氧化物(ITO)涂层的柔性聚乙烯对苯二甲酸乙二醇酯(PET)衬底上并嵌入PANI薄膜,获得了电致发光薄膜材料和有机/无机异质结实验器件ITO/(ZnO NWs-PANI)。有机/无机异质结器件电致发光可调,在相对低的开启电压下呈现室温蓝紫外发光,并且ZnO NWs表面覆盖PANI增加了蓝紫外发光的强度和稳定性;而无PANI的ZnO NWs阵列具有450 nm处的缺陷发射峰,这可能是电子从扩展态锌间隙Zni到价带的跃迁引起的。这些结果表明,基于PANI/ZnO纳米线的复合材料在柔性光电器件方面的应用极具潜力。 相似文献
19.
单晶ZnO纳米线的合成和生长机理研究 总被引:4,自引:0,他引:4
用化学气相输运(CVT)方法合成了直径在20~120nm呈单晶结构的ZnO纳米线.利用场发射扫描电 镜(FESEM)、高分辨透射电镜(HRTEM)以及选区电子衍射(SAED)等技术对ZnO纳米线的生长机理和结构进行 了系统研究,结果表明,纳米线的成核与Au Zn合金催化颗粒的饱和度有直接的关系,先饱和的颗粒上纳米线首 先成核.纳米线顶端合金颗粒组成的变化是导致纳米线生长终止的重要原因,大量纳米线的生长不是同时进行 的.本工作提供了支持纳米线气液固(V L S)生长机理的新实验证据,提出了氧化物纳米线的生长机理. 相似文献
20.
R. Q. Guo J. Nishimura M. Matsumoto D. Nakamura T. Okada 《Applied Physics A: Materials Science & Processing》2008,93(4):843-847
Vertically aligned ZnO nanowires have been successfully synthesized on c-cut sapphire substrates by a catalyst-free nanoparticle-assisted pulsed-laser ablation deposition (NAPLD) in Ar and N2 background gases. In NAPLD, the nanoparticles formed in the background gas by laser ablation are used for the growth of the
nanowires. The surface density of the nanowires can be controlled by varying the density of nanoparticles, which is in turn
achieved by varying ablation laser parameters such as the energy and the repetition rate. When single ZnO nanowire synthesized
in a N2 background gas was excited by 355 nm laser-pulse with a pulse-width of 8 ns, stimulated emission was clearly observed, indicating
high quality of the nanowire. 相似文献