共查询到20条相似文献,搜索用时 31 毫秒
1.
Vertical aligned ZnO nanowires were grown by MOCVD technique on silicon substrate using ZnO and AlN thin films as seed layers. The shape of nanostructures was greatly influenced by the under laying surface. Vertical nanopencils were observed on ZnO/Si, whereas the nanowires on both sapphire and AlN/Si substrate have the similar aspect ratio. XRD patterns suggest that the nanostructures have good crystallinity. High-resolution transmission electron microscopy (HRTEM) confirmed the single crystalline growth of the ZnO nanowires along [0 0 1] direction. Room-temperature photoluminescence (PL) spectra of ZnO nanowires on AlN/Si clearly show a band-edge luminescence accompanied with a visible emission. More interestingly, no visible emission for the nanopencils on ZnO/Si substrates, were observed. 相似文献
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采用自组装技术,利用均聚极性高分子(聚丙烯酰胺、聚乙烯醇等)长分子链作为自组装模板在半导体硅衬底上自组装生长出ZnO纳米线。采用扫描电镜(FE-SEM)和透射电镜(HRTEM)对样品的表面形貌和结构分析表征的结果表明,ZnO纳米线直径约50~80nm、长度大于4μm,具有六方纤锌矿单晶结构,且沿c轴方向择优取向生长。采用室温下光致发光(PL)谱和紫外吸收(UV)光谱对制得的ZnO纳米线的光学性能研究表明,其PL光谱上有较强的紫外发射和较弱的蓝光发射,UV吸收光谱表明样品在紫外区有强的宽带吸收,且随着纳米线粒径的减小,吸收峰出现了蓝移现象。研究探讨了高分子诱导ZnO纳米线自组装定向生长机制、发光机理及其与工艺条件的内在联系。 相似文献
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Synthesis and electrical properties of ZnO nanowires 总被引:1,自引:0,他引:1
Xing X Zheng K Xu H Fang F Shen H Zhang J Zhu J Ye C Cao G Sun D Chen G 《Micron (Oxford, England : 1993)》2006,37(4):370-373
Vertically aligned ZnO nanowires were synthesized on the p(+) silicon chip by modifying the CVD process with a vapor trapping design. Scanning electron microscopy was used to investigate the morphology of as-obtained nanowires. X-ray diffraction showed that the obtained nanowires were ZnO crystalline. The rectifying characteristics of the p-n heterojunction composed of ZnO nanowires and a p(+) silicon chip were observed. The positive turn-on voltage was 0.5V and the reverse saturation current was 0.01mA. These vertically aligned ZnO nanowires showed a low field emission threshold of 4V/microm at a current density of 0.1microA/cm(2). The dependence of emission current density on the electric field followed Fowler-Nordheim relationship. 相似文献
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Nanosphere lithography (NSL) is a successful technique for fabricating highly ordered arrays of ZnO nanowires typically on sapphire and GaN substrates. In this work, we investigate the use of thin ZnO films deposited on Si by pulsed laser deposition (PLD) as the substrate. This has a number of advantages over the alternatives above, including cost and potential scalability of production and it removes any issue of inadvertent n-type doping of nanowires by diffusion from the substrate. We demonstrate ordered arrays of ZnO nanowires, on ZnO-coated substrates by PLD, using a conventional NSL technique with gold as the catalyst. The nanowires were produced by vapor phase transport (VPT) growth in a tube furnace system and grew only on the areas pre-patterned by Au. We have also investigated the growth of ZnO nanowires using ZnO catalyst points deposited by PLD through an NSL mask on a bare silicon substrate. 相似文献
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ZnO nanowires were fabricated on Au coated (0 0 0 1) sapphire substrates by using a pulsed Nd:YAG laser with a ZnO target in furnace. ZnO nanowires have various sizes and shapes with a different substrate position inside a furnace. The length and the diameter of these ZnO nanowires were around 3-4 μm and 120-200 nm, respectively, confirmed by scanning electron microscopy (SEM). The diameter control of the nanowires was achieved by varying the position of substrates. The ultraviolet emission of nanowires from the near band-edge emission (NBE) was observed at room temperature. The formation mechanism and the effect of different position of substrates on the structural and optical properties of ZnO nanowires are discussed. 相似文献
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D. Nakamura K. Okazaki I. A. Palani M. Higashihata T. Okada 《Applied Physics A: Materials Science & Processing》2011,103(4):959-963
Single-crystalline ZnO nanowires on a sapphire substrate have been synthesized by a nanoparticle-assisted pulsed-laser deposition
(NAPLD) using a pure and Sb2O3 doped ZnO target. Low density and vertically well-aligned ZnO nanowires were grown on hexagonal cone-shape ZnO cores by introduction
of a ZnO buffer layer. More than 90% of the ZnO cores of the Sb-induced ZnO nanowires are formed in the same size of 400 nm.
The ZnO nanowires consist of single-crystalline wurtzite ZnO crystal and grow along [0001] direction. The room-temperature
photoluminescence spectrum exhibited a strong ultraviolet emission at around 380 nm and a relatively low broad band emission
in the visible region, indicating a low concentration of structural defect in the nanowires. Sb can be used as one of the
effective additives to control the morphology and alignment of ZnO nanowires synthesized by NAPLD. 相似文献
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Maryam RoozbehiParvaneh Sangpour Ali KhademiAlireza Z. Moshfegh 《Applied Surface Science》2011,257(8):3291-3297
The ZnO nanowires have been synthesized using vapor-liquid-solid (VLS) process on Au catalyst thin film deposited on different substrates including Si(1 0 0), epi-Si(1 0 0), quartz and alumina. The influence of surface roughness of different substrates and two different environments (Ar + H2 and N2) on formation of ZnO nanostructures was investigated. According to AFM observations, the degree of surface roughness of the different substrates is an important factor to form Au islands for growing ZnO nanostructures (nanowires and nanobelts) with different diameters and lengths. Si substrate (without epi-taxy layer) was found that is the best substrate among Si (with epi-taxy layer), alumina and quartz, for the growth of ZnO nanowires with the uniformly small diameter. Scanning electron microscopy (SEM) reveals that different nanostructures including nanobelts, nanowires and microplates have been synthesized depending on types of substrates and gas flow. Observation by transmission electron microscopy (TEM) reveals that the nanostructures are grown by VLS mechanism. The field emission properties of ZnO nanowires grown on the Si(1 0 0) substrate, in various vacuum gaps, were characterized in a UHV chamber at room temperature. Field emission (FE) characterization shows that the turn-on field and the field enhancement factor (β) decrease and increases, respectively, when the vacuum gap (d) increase from 100 to 300 μm. The turn-on emission field and the enhancement factor of ZnO nanowires are found 10 V/μm and 1183 at the vacuum gap of 300 μm. 相似文献
10.
采用化学气相沉积方法,以金做催化剂,在Si (100)衬底上制备了掺AlZnO纳米线阵列.扫描电子显微镜(SEM)表征发现ZnO纳米线的直径在30nm左右.X射线衍射(XRD)图谱上只存在ZnO的(002)衍射峰,说明ZnO纳米线沿c轴择优取向.掺AlZnO纳米线阵列的室温光致发光(PL)谱中出现了3个带边激子发射峰:373nm,375nm,389nm.运用激子理论推算出掺AlZnO纳米线的禁带宽度为3.343eV ,束缚激子结合能为0.156eV;纯ZnO纳米线阵列PL谱中3个带边激子发射
关键词:
光致发光
化学气相沉积(CVD)
激子
ZnO纳米线阵列 相似文献
11.
Qing Zhao 《Solid State Communications》2011,151(22):1650-1653
2D planar field emission devices based on individual ZnO nanowires were achieved on Si/SiO2 substrate via a standard e-beam lithography method. The anode, cathode and ZnO nanowires were on the same substrate; so the electron field emission is changed to 2D. Using e-beam lithography, the emitter (cathode) to anode distance could be precisely controlled. Real time, in situ observation of the planar field emission was realized in a scanning electron microscope. For individual ZnO nanowires, an onset voltage of 200 V was obtained at 1 nA. This innovative approach provides a viable and practical methodology to directly implement into the integrated field emission electrical devices for achieving “on-chip” fabrication. 相似文献
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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
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We have investigated an oxidation of substrate effect on structural morphology of zinc oxide (ZnO) rods. ZnO rods are grown on porous silicon (PS) and on thermally oxidized porous silicon substrates by carbothermal reduction of ZnO powder through chemical vapour transport and condensation. Porous silicon is fabricated by electrochemical etching of silicon in hydrofluoric acid solution. The effects of substrates on morphology and structure of ZnO nanostructures have been studied. The morphology of substrates is studied by atomic force microscopy in contact mode. The texture coefficient of each sample is calculated from X-ray diffraction data that demonstrate random orientation of ZnO rods on oxidized porous silicon substrate. The morphology of structures is investigated by scanning electron microscopy that confirms the surface roughness tends to increase the growth rate of ZnO rods on oxidized PS compared with porous silicon substrate. A green emission has been observed in ZnO structures grown on oxidized PS substrates by photoluminescence measurements. 相似文献
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Aurangzeb Khan Martin E. Kordesch 《Physica E: Low-dimensional Systems and Nanostructures》2005,30(1-2):51-54
ZnO nanowires, nanorods and nanoribbons have been prepared by heating a mixture of ZnO/graphite powders using the thermal evaporation and vapor transport on Si(1 0 0) substrates without any catalyst. The nanostructures are grown as a function of substrate temperature ranging from 900 to 1300 K. These nanostructures are of the size 100–300 nm in diameter or width and several tens of micrometers in length. We studied the influence of the substrate temperature on the luminescent properties of these nanostructures. We observed a strong relationship between the substrate temperature and the green emission band in ZnO, i.e., the photoluminescence study revealed that the green emission peak of the ZnO nanostructures is suppressed relative to the band edge emission when the substrate temperature is decreased from 1300 to 900 K. 相似文献
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J.P. Kar 《Applied Surface Science》2009,255(7):4087-4092
ZnO nanostructures were grown on silicon, porous silicon, ZnO/Si and AlN/Si substrates by low-temperature aqueous synthesis method. The shape of nanostructures greatly depends on the underlying surface. Scattered ZnO nanorods were observed on silicon substrate, whereas aligned ZnO nanowires were obtained by introducing sputtered ZnO film as a seed layer. Furthermore, both the combination of nanorods and the bunch of nanowires were found on porous silicon substrates, whereas platelet-like morphology was observed on AlN/Si substrates. XRD patterns suggest the crystalline nature of aqueous-grown ZnO nanostructures and high-resolution transmission electron microscopy images confirm the single-crystalline growth of the ZnO nanorods along [0 0 1] direction. Room-temperature photoluminescence characterization clearly shows a band-edge luminescence along with a visible luminescence in the yellow spectral range. 相似文献
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Kyung Ah Jeon Hyo Jeong Son Chang Eun Kim Jong Hoon Kim Sang Yeol Lee 《Physica E: Low-dimensional Systems and Nanostructures》2007,37(1-2):222
ZnO nanowires were fabricated on c-plane (0 0 0 1), a-plane (1 1 2¯ 0) sapphire, and boron doped p-type (1 0 0) Si substrates in vacuum furnace by simple physical vapor deposition. Room temperature photoluminescence spectra of the nanowires show the near band-edge emission and the deep-level green light emission. The ZnO nanowires formed on sapphire (1 1 2¯ 0) substrates exhibited enhancement on optical properties and better crystalline structures than those of nanowires grown on other substrates. The formation mechanism and the effect of substrate direction on structural and optical properties of the nanowires are discussed. 相似文献
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J.P. Kar M. Kumar J.H. Choi S.N. Das S.Y. Choi J.M. Myoung 《Solid State Communications》2009,149(33-34):1337-1341
In this paper, the formation of a p–n ZnO thin film-nanowires hybrid homojunction on silicon substrate has been investigated. P-type ZnO thin film is formed by both e-beam evaporation and RF magnetron sputtering techniques. In order to fabricate 3-dimentional hybrid structures, ZnO nanowires were grown on p-type ZnO films by metal organic chemical vapor deposition techniques. The X-ray diffraction results showed that both ZnO thin films and nanowires are -axis oriented. The formation of p–n ZnO homojunction is verified by current–voltage measurements. Typical diode behavior and photoconductivity were observed in both designs. 相似文献
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Not only vertically aligned ZnO nanowires but also horizontally aligned ZnO nanowires have been successfully grown on the annealed (0 0 0 1) c-cut and (1 1 2 0) a-cut sapphire substrates, respectively using catalyst-free nanoparticle-assisted pulsed-laser ablation deposition (NAPLD). The as-synthesized ZnO nanowires exhibit an ultraviolet emission at around 390 nm and the absent green emission under room temperature. The single ZnO nanowire was collected in the electrode gap by dielectrophoresis (DEP). Under the optical pumping, the single ZnO nanowire exhibited UV emission at around 390 nm with several sharp peaks whose energy spacings are almost constant, which greatly differs from the broad UV emission of the film with many nanowires, suggesting ZnO nanowires as candidates for laser media. The single ZnO nanowire showed polarized photoluminescence (PL). The as-synthesized ZnO nanowires could find many interesting applications in short-wavelength light-emitting diode (LED), laser diode and gas sensor. 相似文献
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Tribological characteristics of ZnO nanowires investigated by atomic force microscope 总被引:1,自引:0,他引:1
Koo-Hyun Chung Hyun-Joon Kim Li-Yu Lin Dae-Eun Kim 《Applied Physics A: Materials Science & Processing》2008,92(2):267-274
Zinc oxide (ZnO) nanowires have attracted great interest in nanodevices. In this work, the tribological characteristics of
vertically grown ZnO nanowires obtained by metalorganic chemical vapor deposition were investigated by using an atomic force
microscope (AFM). The ZnO nanowires were slid against flattened silicon and diamond-coated AFM probes under 50–150 nN normal
force while monitoring the frictional force. The wear of the ZnO nanowires was observed by a scanning electron microscope
and quantified based on Archard’s wear law. Also, the wear debris accumulated on the silicon probe was analyzed by using a
transmission electron microscope (TEM). The results showed that the wear of ZnO nanowires slid against the silicon probe was
extremely small. However, when the ZnO nanowires were slid against the diamond-coated probe, the wear coefficients ranged
from 0.006 to 0.162, which correspond to the range of severe wear at the macroscale. It was also shown that the friction coefficient
decreased from 0.30 to 0.25 as the sliding cycles increased. From TEM observation, it was found that the ZnO wear debris was
mainly amorphous in structure. Also, crystalline ZnO nanoparticles were observed among the wear debris.
PACS 07.79.Lh; 46.55.+d; 81.07.Bc 相似文献
20.
Catalyst-free MOCVD growth of aligned ZnO nanotip arrays on silicon substrate with controlled tip shape 总被引:1,自引:0,他引:1
Quasi-aligned zinc oxide nanotip arrays have been grown by MOCVD without using catalyst. The tip shape was controlled systematically by varying the gas flow rate, demonstrating a technique for growing tip arrays of ZnO on silicon. This technology can be large-scale on the wafer level and it has the potential to be directly integrated with clean room silicon technology. The diameter of these ZnO nanowires or nanotips could be controlled by the varying of source flow rate, providing a simple but unique way of fabricating ZnO nanotip arrays for application in field emission and nanogenerators. 相似文献