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1.
ZnO nanobelt/nanowire Schottky diodes formed by dielectrophoresis alignment across au electrodes 总被引:3,自引:0,他引:3
Rectifying diodes of single nanobelt/nanowire-based devices have been fabricated by aligning single ZnO nanobelts/nanowires across paired Au electrodes using dielectrophoresis. A current of 0.5 microA at 1.5 V forward bias has been received, and the diode can bear an applied voltage of up to 10 V. The ideality factor of the diode is approximately 3, and the on-to-off current ratio is as high as 2,000. The detailed IV characteristics of the Schottky diodes have been investigated at low temperatures. The formation of the Schottky diodes is suggested due to the asymmetric contacts formed in the dielectrophoresis aligning process. 相似文献
2.
Lee WK Robinson JT Gunlycke D Stine RR Tamanaha CR King WP Sheehan PE 《Nano letters》2011,11(12):5461-5464
We demonstrated the fabrication of graphene nanoribbons (GNRs) as narrow as 35 nm created using scanning probe lithography to deposit a polymer mask(1-3) and then fluorinating the sample to isolate the masked graphene from the surrounding wide band gap fluorographene. The polymer protected the GNR from atmospheric adsorbates while the adjacent fluorographene stably p-doped the GNRs which had electron mobilities of ~2700 cm2/(V·s). Chemical isolation of the GNR enabled resetting the device to nearly pristine graphene. 相似文献
3.
Chuvilin A Bichoutskaia E Gimenez-Lopez MC Chamberlain TW Rance GA Kuganathan N Biskupek J Kaiser U Khlobystov AN 《Nature materials》2011,10(9):687-692
The ability to tune the properties of graphene nanoribbons (GNRs) through modification of the nanoribbon's width and edge structure widens the potential applications of graphene in electronic devices. Although assembly of GNRs has been recently possible, current methods suffer from limited control of their atomic structure, or require the careful organization of precursors on atomically flat surfaces under ultra-high vacuum conditions. Here we demonstrate that a GNR can self-assemble from a random mixture of molecular precursors within a single-walled carbon nanotube, which ensures propagation of the nanoribbon in one dimension and determines its width. The sulphur-terminated dangling bonds of the GNR make these otherwise unstable nanoribbons thermodynamically viable over other forms of carbon. Electron microscopy reveals elliptical distortion of the nanotube, as well as helical twist and screw-like motion of the nanoribbon. These effects suggest novel ways of controlling the properties of these nanomaterials, such as the electronic band gap and the concentration of charge carriers. 相似文献
4.
利用第一性原理研究了两种具有边缘缺陷石墨烯纳米结的自旋输运,即边界氢原子饱和和未被饱和两种情况。结果表明:边缘缺陷改变了电子的输运行为。对于完整的石墨烯纳米带,两种自旋的电子在费米能级附近是完全简并的;对于含有边缘缺陷的石墨烯纳米结,两种自旋的电子在费米能级附近的很大能量范围内表现出自旋分离。电子局域态密度可进一步说明这种输运行为。这些纳米结可产生与自旋相关的极化电流。特别对于未饱和的缺陷结,在任何偏压下都有较高的自旋滤波效率。 相似文献
5.
Oh BY Han JW Seo DS Kim KY Baek SH Jang HS Kim JH 《Journal of nanoscience and nanotechnology》2012,12(7):5330-5335
We report the structural, electrical, and optical characteristics of Al-doped ZnO (ZnO:Al) films deposited on glass by atomic layer deposition (ALD) with various Al2O3 film contents for use as transparent electrodes. Unlike films fabricated by a sputtering method, the diffraction peak position of the films deposited by ALD progressively moved to a higher angle with increasing Al2O3 film content. This indicates that Zn sites were effectively replaced by Al, due to layer-by-layer growth mechanism of ALD process which is based on alternate self-limiting surface chemical reactions. By adjusting the Al2O3 film content, a ZnO:Al film with low electrical resistivity (9.84 x 10(-4) Omega cm) was obtained at an Al2O3 film content of 3.17%, where the Al concentration, carrier mobility, optical transmittance, and bandgap energy were 2.8 wt%, 11.20 cm2 V(-1) s(-1), 94.23%, and 3.6 eV, respectively. Moreover, the estimated figure of merit value of our best sample was 8.2 m7Omega(-1). These results suggest that ZnO:Al films deposited by ALD could be useful for electronic devices in which especially require 3-dimensional conformal deposition of the transparent electrode and surface passivation. 相似文献
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7.
Prediction of very large values of magnetoresistance in a graphene nanoribbon device 总被引:2,自引:0,他引:2
Graphene has emerged as a versatile material with outstanding electronic properties that could prove useful in many device applications. Recently, the demonstration of spin injection into graphene and the observation of long spin relaxation times and lengths have suggested that graphene could play a role in 'spintronic' devices that manipulate electron spin rather than charge. In particular it has been found that zigzag graphene nanoribbons have magnetic (or spin) states at their edges, and that these states can be either antiparallel or parallel. Here we report the results of first-principles simulations that predict that spin-valve devices based on graphene nanoribbons will exhibit magnetoresistance values that are thousands of times higher than previously reported experimental values. These remarkable values can be linked to the unique symmetry of the band structure in the nanoribbons. We also show that it is possible to manipulate the band structure of the nanoribbons to generate highly spin-polarized currents. 相似文献
8.
Shuo Liu Qingliang Liao Zheng Zhang Xiankun Zhang Shengnan Lu Lixin Zhou Mengyu Hong Zhuo Kang Yue Zhang 《Nano Research》2017,10(10):3476-3485
The mixed-dimensional van der Waals (vdW) heterostructure is a promising building block for strained electronics and optoelectronics because it avoids the bond fracture and atomic reconstruction under strain.We propose a novel mixed-dimensional vdW heterostructure between two-dimensional graphene and a one-dimensional ZnO nanowire for high-performance photosensing.By utilizing the piezoelectric properties of ZnO,strain modulation was accomplished in the mixed-dimensional vdW heterostructure to optimize the device performance.By combining the ultrahigh electrons transfer speed in graphene and the extremely long life time of holes in ZnO,an outstanding responsivity of 1.87 × 105 A/W was achieved.Under a tensile strain of only 0.44% on the ZnO nanowire,the responsivity was enhanced by 26%.A competitive model was proposed,in which the performance enhancement is due to the efficient promotion of the injection of photogenerated electrons from the ZnO into the graphene caused by the strain-induced positive piezopotential.Our study provides a strain-engineering strategy for controlling the behavior of the photocarriers in the mixed-dimensional vdW heterostructure,which can be also applied to other similar systems in the future. 相似文献
9.
We study graphene nanoribbon (GNR) interconnects obtained from graphene grown by chemical vapor deposition (CVD). We report low- and high-field electrical measurements over a wide temperature range, from 1.7 to 900 K. Room temperature mobilities range from 100 to 500 cm(2)·V(-1)·s(-1), comparable to GNRs from exfoliated graphene, suggesting that bulk defects or grain boundaries play little role in devices smaller than the CVD graphene crystallite size. At high-field, peak current densities are limited by Joule heating, but a small amount of thermal engineering allows us to reach ~2 × 10(9) A/cm(2), the highest reported for nanoscale CVD graphene interconnects. At temperatures below ~5 K, short GNRs act as quantum dots with dimensions comparable to their lengths, highlighting the role of metal contacts in limiting transport. Our study illustrates opportunities for CVD-grown GNRs, while revealing variability and contacts as remaining future challenges. 相似文献
10.
Hiroyuki Hasegawa Yutaka Noguchi Rieko Ueda Tohru Kubota Shinro Mashiko 《Thin solid films》2008,516(9):2491-2494
We obtained organic Mott insulator nanowire by using the Nanoscale-electrocrystallization. The ac electrocrystallization provided nanowires only in the gap between two electrodes though dc yielded them over the anode surface. These nanowires ranged in width from 50 nm to several hundred nm and were several μm in length. We also measured their i-V characteristics. 相似文献
11.
We present a semi-analytical model incorporating the effects of edge bond relaxation, the third nearest neighbor interactions,
and edge scattering in graphene nanoribbon field-effect transistors (GNRFETs) with armchair-edge GNR (AGNR) channels. Unlike
carbon nanotubes (CNTs) which do not have edges, the existence of edges in the AGNRs has a significant effect on the quantum
capacitance and ballistic I-V characteristics of GNRFETs. For an AGNR with an index of m=3p, the band gap decreases and the ON current increases whereas for an AGNR with an index of m=3p+1, the quantum capacitance increases and the ON current decreases. The effect of edge scattering, which reduces the ON current,
is also included in the model.
This article is published with open access at Springerlink.com 相似文献
12.
Yufu Zhu Fei Deng Chaoying Ni Wenzhong Shen 《Journal of Materials Science: Materials in Electronics》2014,25(10):4547-4552
Novel ZnO core/shell nanostructures were constructed by depositing a porous ZnO layer directly on the surfaces of pre-fabricated ZnO nanowires through a facile chemical method. The morphology and structure of the obtained products have been investigated by field-emission scanning electron microscopy, high-resolution transmission electron microscopy and X-ray diffraction analysis. In these unique nanostructures, the porous overlayer exhibits a large surface area for sufficient dye loading to enhance light harvesting and the ZnO nanowire cores provide direct conduction pathways for the photogenerated electron transport to diminish the chance of electron recombination. The obtained ZnO nanostructures were used as photoanode material in dye-sensitized solar cell which showed an increase in performance of 141 % compared with an equivalent solar cell employing ZnO nanowire arrays as photoanode. This result was achieved mainly due to an increase in photogenerated current density directly resulting from improved light harvesting of the porous layer. 相似文献
13.
采用光刻和射频磁控溅射技术在Si衬底上制备了图形化的ZnO种子层薄膜。分别采用气相榆运和水热合成法,制备了最小单元为30μm的图形化的ZnO纳米线阵列。X射线衍射(XRD)分析显示单晶纳米线阵列具有高度的c轴[001]择优取向生长性质,从扫描电子显微镜(SEM)照片看出,阵列图形完整清晰,边缘整齐,纳米线阵列在室温下光致发光(PL)谱线中在380hm左右具有强烈的紫外发射峰,可见光区域发射峰得到了抑制,证明ZnO纳米线阵列氧空位缺陷少,晶体质量高。 相似文献
14.
Flexible paper-like ZnO nanowire films are fabricated and the effect of L-lysine passivation of the nanowire surfaces on improving the UV photoresponse is studied. We prepare three types of nanowires with different defect contents, and find that the L-lysine treatment can suppress the oxygen-vacancy-related photoluminescence as well as enhance the UV photoconduction. The nanowires with fewer defects gain larger enhancement of UV photoconduction after L-lysine treatment. Reproducible UV photoresponse of the devices in humid air is obtained due to L-lysine surface passivation, ruling out the influence of water molecules in degrading the UV photocurrent. 相似文献
15.
A photovoltaic device was successfully grown solely based on the single ZnO p-n homojunction nanowire. The ZnO nanowire p-n diode consists of an as-grown n-type segment and an in situ arsenic-doped p-type segment. This p-n homojunction acts as a good photovoltaic cell, producing a photocurrent almost 45 times larger than the dark current under reverse-biased conditions. Our results demonstrate that the present ZnO p-n homojunction nanowire can be used as a self-powered ultraviolet photodetector as well as a photovoltaic cell, which can also be used as an ultralow electrical power source for nanoscale electronic, optoelectronic and medical devices. 相似文献
16.
The advent of graphene heralded by the recent studies on carbon based conducting polymer composites has been a motivation for the use of graphene as an electromagnetic interference (EMI) shielding material. One of the variants of graphene, graphene nanoribbon (GNR) shows remarkably different properties from graphene. The EMI shielding effectiveness of the composite material mainly depends on fillers’ intrinsic conductivity, dielectric constant and aspect ratio. We have synthesized graphene nanoribbon (GNR) – Polyaniline (PANI) – epoxy composite film for effective shielding material in the X-band frequency range of 8.2–12.4 (GHz). We have performed detailed studies of the EMI shielding effect and the performance of the composite and found that the composite shows ∼−40 dB shielding which is sufficient to shield more than 95% of the EM waves in X Band. We checked the shielding effectiveness of the composite film by varying the GNR percentage and the thickness of the film. The strength properties of the synthesized composited were also studied with a aim to have a material having both high strength and EMI shielding properties. 相似文献
17.
The equilibrium piezoelectric potential distribution in a deformed ZnO semiconductive nanowire has been systematically investigated
in order to reveal its dependence on the donor concentration, applied force, and geometric parameters. In particular, the
donor concentration markedly affects the magnitude and distribution of the electric potential. At a donor concentration of
N
D>1018 cm−3, the piezopotential is almost entirely screened. Among the other parameters, a variation in the length of the nanowire does
not significantly affect the potential distribution.
相似文献
18.
The emission spectrum of individual high-quality ZnO nanowires consists of a series of Fabry-Pérot-like eigenmodes that extend far below the band gap of ZnO. Spatially resolved luminescence spectroscopy shows that light is emitted predominantly at both wire ends, with identical spectra reflecting standing wave polariton eigenmodes. The intensity of the modes increases supralinearly with the excitation intensity, indicating that the mode population is governed by scattering among polaritons. Due to strong light-matter interaction, light emission from a ZnO nanowire is not dictated by the electronic band diagram of ZnO but depends also on the wire geometry and the excitation intensity. Delocalized polaritons provide a natural explanation for the pronounced subwavelength guiding in ZnO wires that has been reported previously. 相似文献
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纳米结构的ZnO由于具有优异的光、电、磁、声等性能,已经成为光电、化学、催化、压电等领域中聚焦的研究热点之一.不同纳米结构的ZnO其制备方法不同,着重概述了采用化学气相沉积(CVD)工艺制备ZnO纳米材料,包括直接热分解、高温加热锌粉、碳热还原法以及金属有机气相沉积(MOCVD)4种方法,重点讨论了不同锌源和氧源对ZnO纳米结构的影响规律,并初步探讨了ZnO的VLS与VS生长机理,同时展望了ZnO在各领域中的最新应用. 相似文献