氧化锌纳米线的场发射

热蒸发法在硅基底上制备了任意取向的氧化锌纳米线阵列。经过热蒸发过程，硅基底表面覆盖了大量均匀分布的氧化锌岛，在这些岛上生长出了直径为几十纳米的非定向纳米线。出于实用考虑，基底周围的温度在制备过程中保持在500°C以下。从这些氧化锌纳米线获得了场发射。测得10μA/cm2所对应的开启场强为3.0V/μm。并且用透明阳极技术研究了发射中心分布。观察到场发射来自于整个样品表面。从这些结果可以看出氧化锌纳米线在平板显示器中有着巨大的应用潜力.     

场电子发射研究现状及理论概述

由于场发射研究日趋重要，文章就场发射理论的起源，研究现状进行了总结，介绍了电子在几种不同类型材料的场发射理论模型，并对理论本身存在的问题进行了述评，着重指出其理论缺陷的实质及完善的可能性。     

紫外光激发下氧化锌纳米线的发光特性研究

室温条件下,用355 nm的激光激发氧化锌纳米线,测量了其发光光谱.观察到半宽度较小、峰值波长约382 nm的紫光峰和半宽度较宽、峰值波长约507 nm的绿光峰;两峰的发光强度随激发光功率密度的变化而变化,且均存在饱和效应,但各自的变化规律及饱和值的大小不同;紫光峰的中心波长随激发光功率密度的增加而发生了明显的红移.对两峰产生的机理、强度饱和值存在的原由、强度随激发光功率密度变化及紫光峰红移的起因进行了分析.     

碳化硅纳米线的电子发射特性

以聚碳硅烷为原料,通过1 200 ℃高温裂解工艺制备了碳化硅纳米线,并采用碳化硅纳米线作为高功率微波源用阴极材料,进行了电子发射实验。结果表明：与天鹅绒阴极材料相比,碳化硅纳米线具有更高的电子发射电流密度,在115 kV外加激励脉冲高压下,电子发射密度为23.7 kA/cm2,而天鹅绒材料为14.0 kA/cm2,并具有更好的电子发射品质及更长的使用寿命。因此碳化硅纳米线作为高功率微波源用阴极,具有很好的应用潜力。     

带栅极纳米线冷阴极的场增强因子研究

场增强因子是体现场发射冷阴极器件性能优劣的重要参数.利用静电场理论给出了一种带栅极(normal-gated)纳米线冷阴极的场增强因子表示式β=k₁{N²·(L-d₁)²+［1/k₁+(L-d₁)］²}^1/2，且进一步分析了几何参数对场增强因子的影响.结果表明，纳米线突出栅孔的部分(L-d₁)与栅孔半径越大，则场增强因子越大；而纳米线半径越小，则场增强因子越大；当L远大于d₁时满足β∝L/r₀.其中N=N₁(k₁r₀)/N₀(k₁r₀)，N₀(k₁r₀)和N₁(k₁r₀)分别代表零阶和一阶Neumann函数，k₁=0.8936/R，R为栅孔半径，L为纳米线长度，r₀为纳米线半径，d₁表示阴极与栅极间距.     

类富勒烯纳米晶CNx薄膜及其场致电子发射特性

利用微波等离子体增强化学气相沉积技术制备出了CNx薄膜,并利用x射线光电子能谱、x射线衍射、扫描电子显微镜和Raman光谱等测试手段对所制备的CNx薄膜的微结构和成分进行了分析.研究了其场致电子发射特性.发现薄膜的结构和场发射特性与反应系中的甲烷、氮气及氢气的流量比有关,当甲烷、氢气及氮气流量比为8/50/50sccm时,制备的薄膜具有弯曲层状的纳米石墨晶体结构(类富勒烯结构)和很好的场发射特性.场发射阈值电场降低至1.1V/μm.当电场为5.9V/μm时,平均电流密度达70μA/cm2,发射点密度大于1×104cm-2.     

类富勒烯纳米晶CNx薄膜及其场致电子发射特性

利用微波等离子体增强化学气相沉积技术制备出了CN_x薄膜,并利用x射线光电子能谱、x射线衍射、扫描电子显微镜和Raman光谱等测试手段对所制备的CN_x薄膜的微结构和成分进行了分析.研究了其场致电子发射特性.发现薄膜的结构和场发射特性与反应系中的甲烷、氮气及氢气的流量比有关,当甲烷、氢气及氮气流量比为8/50/50 sccm时,制备的薄膜具有弯曲层状的纳米石墨晶体结构（类富勒烯结构）和很好的场发射特性.场发射阈值电场降低至1.1V/μm.当电场为5.9V/μm时,平 关键词： 类富勒烯 x薄膜')" href="#">CN_x薄膜 场致电子发射 微波等离子体增强化学气相沉积     

宽带隙薄膜材料场电子发射研究的背景、现状和问题

介绍了以金刚石为代表的宽带隙薄膜材料场电子发射研究背景和现状,对金刚石、类金刚石（ＤＬＣ）、立方氮化硼（ｃ－ＢＮ）、氮化铝（Ａ１Ｎ）和碳化硅（ＳｉＣ）薄膜场电子发射研究的进展进行了评述,着重介绍了发射性能与薄膜的结构特征、杂质含量和处理方法间的关系,并讨论了研究中存在的问题。     

平行栅结构氧化锌场致发射显示器的研制

用陈化处理过的锌粉为原料,采用高温气相氧化法制备四针状氧化锌材料。应用厚膜、光刻工艺和丝网印刷法制作氧化锌场发射阴极阵列。将阴极板与阳极荧光板制成了5英寸(12.7 cm)单色平行栅结构场致发射显示器(FED)并对其进行了场发射性能测试。分析讨论了影响发射性能的栅极电压、阳极电压以及阴极厚度等参数。该FED在约4000 V阳极电压和300 V栅极电压的驱动下能实现全屏发光。实验结果表明,氧化锌平行栅结构FED具有良好的栅极调控作用,场致发射性能良好,具有良好的应用前景。     

生长温度对纳米氧化锌场发射性能的影响

采用锌粉和银粉为蒸发源,用热蒸发法不同温度下制备了四针状纳米氧化锌,并以单独的锌粉做对照。采用扫描电子显微镜(SEM)观察其形貌,X射线衍射(XRD)谱表征其晶体结构。采用丝网印刷方法将其制备为场致电子发射阴极,将阴极与印刷有荧光粉的阳极板组装成二极结构场致发射显示屏,并进行了场致电子发射特性对比实验。结果表明较高温度制备的氧化锌具有较好的场致发射性能;掺杂银粉的蒸发源制备的样品的发射性能明显优于没有掺杂银粉的样品。实验证明ZnO是一种优良的场致发射冷阴极材料,在真空电子方面具有广阔的应用前景。     

InN纳米线的低压化学气相沉积及其场发射特性研究

利用低压化学气相沉积方法在以Au作催化剂的Si衬底上生长了InN纳米线. 扫描电子显微镜分析表明，这些纳米线的直径在60—100 nm的范围内, 而其长度大于1 μm.高分辨透射电子显微镜图像表明，合成的纳米线中含有六方相和立方相的InN晶体.这些InN纳米线具有良好的场发射特性和稳定的场发射电流，其开启场为10.02 V/μm(电流密度为10 μA/cm²)，在24 V/μm 的电场下，其电流密度达到5.5 mA/cm².此外，对InN纳米线的场发射机理也进行了讨论. 关键词： InN纳米线 场电子发射 非线性Fower-Nordheim曲线     

Preparation of few-layer graphene-capped boron nanowires and their field emission properties

Large-area boron nanowire(BNW) films were fabricated on the Si(111) substrate by chemical vapor deposition(CVD). The average diameter of the BNWs is about 20 nm, with lengths of 5–10 μm. Then, graphene-capped boron nanowires(GC-BNWs) were obtained by microwave plasma chemical vapor deposition(MPCVD). Characterization by scanning electron microscopy indicates that few-layer graphene covers the surface of the boron nanowires. Field emission measurements of the BNWs and GC-BNW films show that the GC-BNW films have a lower turn-on electric field than the BNW films.     

2D planar field emission devices based on individual ZnO nanowires

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.     

合成温度对Ce掺杂SiC纳米线的制备及场发射性能的影响研究

本文利用化学气相反应(CVR)法, 系统研究了不同温度对Ce掺杂的SiC纳米线及其场发射性能的影响规律. 利用扫描电镜(SEM)、透射电镜(TEM)、选区电子衍射(SAED)、X射线衍射(XRD)对所得产物进行了表征, 并对其场发射性能进行了测试. 结果表明: 所得产物为具有立方结构的β-SiC晶体, 随着温度的升高, 纳米线逐渐变的弯曲, Ce的含量降低, 产物的开启电场和阈值电场先升高后降低. 当合成温度为1250 ℃, Ce的含量为0.27 at%, 产物的场发射性能最佳,开启电场和阈值电场分别为2.5 V/μm和5.2 V/μm. 关键词： 合成温度 SiC纳米线 场发射性能     

Peculiarities of electron field emission from ZnO nanocrystals and nanostructured films

ZnO microcrystals and nanocrystals were grown on silicon substrates by condensation from vapour phase. Nanostructured ZnO films were deposited by plasma enhanced metal organic chemical vapour deposition (PEMOCVD). The parameters of field emission, namely form-factor β and work function , were calculated for ZnO structures by the help of the Fowler–Nordheim equation. The work functions from ZnO nanostructured films were evaluated by a comparison method. The density of emission current from ZnO nanostructures reaches 0.6 mA/cm² at electric force F=2.110⁵ V/cm. During repeatable measurements β changes from 5.810⁴ to 2.310⁶ cm⁻¹, indicating improvement of field emission. Obtained values of work functions were 3.7±0.37 eV and 2.9–3.2 eV for ZnO nanostructures and ZnO films respectively.     

Enhanced field emission characteristics of zinc oxide mixed carbon nano-tubes films

A composite material of Zinc oxide and carbon nano-tubes (ZnO-CNTs) paste was synthesized by mixing multi-wall CNTs, ZnO nano-grains and organic vehicles. The microstructures and the morphologies of screen-printed films were characterized by field-emission scanning electron microscope. Results show that ZnO flakes geometrically matched with CNTs by filling into the interspaces of CNTs or directly covering upon CNTs. The field emission characteristics of films are found to be greatly effected by ZnO nano-grains. Especially, the turn-on electric field of ZnO-CNT film (1.17 V/μm) which is far lower than that of usual CNT films (1.70 V/μm). Furthermore, except that better emission stability is achieved, brightness and emission uniformity are notably enhanced as well. It can be speculated that the special microstructures of ZnO mixed CNT films dominate the enhanced electrical conductivity, thermal conductivity, and effective emitters.     

Piezoelectric power generation from zinc oxide nanowires grown on paper substrate

In this study, we demonstrate piezoelectric power generation from zinc oxide (ZnO) nanowires grown on paper substrate. Vertically aligned ZnO nanowires are deflected by an atomic force microscopy (AFM) tip in contact mode which generates an output voltage of up to 7 mV. Furthermore, the effects of different parameters mainly influencing the magnitude of the output voltage are discussed. We expect that due to its simplicity, this approach represents an important step within the development of nanoscale power generators. It offers a promising alternative powering source for the next generation of nanodevices on disposable paper. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth and electron field emission of ZnO nanorods on diamond films

Zinc oxide (ZnO) nanorods grown on chemical vapor deposited diamond films by thermal vapor transport method have been investigated. In the initial growth status, the semi-spherical ZnO nuclei were preferably deposited near the growth steps on the terraces and the boundaries of diamond grains. With increasing the growth time, the [0 0 0 1] orientated ZnO nanorods appeared and further covered the whole diamond film. It is found that the size of diamond grains would determine the diameter of ZnO nanorods. The electron field emission properties of the ZnO nanorods/diamond system have been significantly improved with respect to pure diamond film. The feature of the ZnO nanorods grown on diamond films played an important role in further enhancing the electron field emission performances.