共查询到19条相似文献,搜索用时 140 毫秒
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场电子发射是一种独特的量子隧穿效应,也是真空微电子学的基础之一。基于场发射技术的冷阴极发射体一直被视为未来理想的电子发射阴极。石墨烯是一种具备单层碳原子结构的新型碳材料,其电子迁移率高、机械强度高、热导率高,具有稳定的物理化学特性,因此受到科研工作者的广泛关注。与此同时石墨烯具有较高的长径比(横向尺寸与厚度的比值),这一结构特性能够获得较大的场增强因子。石墨烯的上述特性使得其成为具有广阔应用前景的场发射阴极。本文主要综述石墨烯场发射理论的研究进展、石墨烯/石墨烯基场发射阴极的研究现状、场发射阴极结构以及场发射阴极的制备方法,并对场发射领域的石墨烯研究进行了展望。 相似文献
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利用热蒸发和丝网印刷技术在玻璃基底上成功制备了氧化锌纳米线表面传导场发射阴极阵列,并测试其场发射性能。扫描电镜表明,在氩气和氧气流量分别为60和1mL/min,反应温度550℃保温30min条件下制备的氧化锌纳米线均匀垂直生长在玻璃基底上,直径大约在80~200nm,长度〉7μm。场发射测试表明,在阳压2000V和阴阳间距为500μm时,ZnO纳米线表面传导场发射阴极的开启电压为70V;在栅压为96V时,电子发射效率为26.2%,高于传统报道的表面传导电子发射器件,在经过80min的老练后发射接近稳定,平均发射电流接近135μA,表明ZnO纳米线表面传导场发射阴极有着稳定高效的场发射性能。 相似文献
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场发射枪提供亮度高、相干性好的电子源,使透射电子赤微镜在纳米尺度分析和获取更全面信息方面开拓了新的领域。本文在介绍肖脱基场发射枪和冷场发射枪基本特性的基础上,简述了场发射枪透射电镜在纳米全分析、能量选择成象、相干电子衍射效应及电子全息术中的应用。 相似文献
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阴极作为强流电子束的起点,对高功率微波源的性能具有重要影响。石墨是高功率源用爆炸发射阴极的常用材料,具有高压重频条件下运行稳定和长寿命的优点。使用具有高长径比、低发射阈值的碳纤维对石墨阴极进行复合,采用场发射及高功率微波测试平台,对比分析纯石墨阴极及碳纤维复合石墨阴极的场发射性能、强流电子发射性能及输出微波特性,结合阴极的微观结构表征,研究碳纤维复合对石墨阴极电子发射性能的影响规律。研究表明:与鳞片石墨阴极相比,40%(质量分数)碳纤维复合石墨阴极的场发射阈值电场由143 kV/cm降低到119 kV/cm,降低了约16.8%,二极管电压为480 kV时输出的微波脉宽与峰值分别提高了13.5%,5.7%。同时考虑到碳纤维在爆炸电子发射过程中结构稳定性的特点,碳纤维的复合也有利于阴极使用寿命的提高。 相似文献
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阴极作为强流电子束的起点,对高功率微波源的性能具有重要影响。石墨是高功率源用爆炸发射阴极的常用材料,具有高压重频条件下运行稳定和长寿命的优点。使用具有高长径比、低发射阈值的碳纤维对石墨阴极进行复合,采用场发射及高功率微波测试平台,对比分析纯石墨阴极及碳纤维复合石墨阴极的场发射性能、强流电子发射性能及输出微波特性,结合阴极的微观结构表征,研究碳纤维复合对石墨阴极电子发射性能的影响规律。研究表明:与鳞片石墨阴极相比,40%(质量分数)碳纤维复合石墨阴极的场发射阈值电场由143 kV/cm降低到119 kV/cm,降低了约16.8%,二极管电压为480 kV时输出的微波脉宽与峰值分别提高了13.5%,5.7%。同时考虑到碳纤维在爆炸电子发射过程中结构稳定性的特点,碳纤维的复合也有利于阴极使用寿命的提高。 相似文献
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阴极作为强流电子束的起点,对高功率微波源的性能具有重要影响。石墨是高功率源用爆炸发射阴极的常用材料,具有高压重频条件下运行稳定和长寿命的优点。使用具有高长径比、低发射阈值的碳纤维对石墨阴极进行复合,采用场发射及高功率微波测试平台,对比分析纯石墨阴极及碳纤维复合石墨阴极的场发射性能、强流电子发射性能及输出微波特性,结合阴极的微观结构表征,研究碳纤维复合对石墨阴极电子发射性能的影响规律。研究表明:与鳞片石墨阴极相比,40%(质量分数)碳纤维复合石墨阴极的场发射阈值电场由143 kV/cm降低到119 kV/cm,降低了约16.8%,二极管电压为480 kV时输出的微波脉宽与峰值分别提高了13.5%,5.7%。同时考虑到碳纤维在爆炸电子发射过程中结构稳定性的特点,碳纤维的复合也有利于阴极使用寿命的提高。 相似文献
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模拟研究常闭和常开工作模式下的平面栅极型碳纳米管场发射电子源 总被引:1,自引:1,他引:0
采用数值模拟的方法对比性地研究了常闭和常开工作模式下平面栅极型碳纳米管场发射电子源.静电场的数值计算结果显示:常闭工作模式下该电子源中阴极电极的表面电场分布不均匀,边缘处的高电场易导致其上的碳纳米管烧毁,从而引起场发射电流衰减.为了解决此问题,提出将常开工作模式用于该电子源,并证实常开工作模式能够用于该电子源,并有利于解决电流衰减问题.因此,相对于常闭工作模式,常开工作模式更适合平面栅极型碳纳米管场发射电子源. 相似文献
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Qilong Wang Cairu Yu Yusong Di Zhuoya Zhu Xiaobing Zhang Chen Li 《Fullerenes, Nanotubes and Carbon Nanostructures》2016,24(4):273-277
High-current-density field emitters are considered as the potential and necessary components for compact high definition x-ray sources and high-power cold cathode microwave amplifiers. In this report, high-current-density field emission from self-heating printed carbon nanotubes is introduced. Large emission current causes large heat that increases the temperature of the emitters. The temperature is estimated to be more than ~1600 K. Localized surface field and high temperature both drive more electrons escaping from the emitters, and the maximum current density is larger than ~2.7 A/cm2 that will satisfy the need of most vacuum electron devices including x-ray sources and microwave electron devices. 相似文献
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Shenghan Zhou Ke Chen Matthew Thomas Cole Zhenjun Li Jun Chen Chi Li Qing Dai 《Advanced materials (Deerfield Beach, Fla.)》2019,31(45)
The search for electron sources with simultaneous optimal spatial and temporal resolution has become an area of intense activity for a wide variety of applications in the emerging fields of lightwave electronics and attosecond science. Most recently, increasing efforts are focused on the investigation of ultrafast field‐emission phenomena of nanomaterials, which not only are fascinating from a fundamental scientific point of view, but also are of interest for a range of potential applications. Here, the current state‐of‐the‐art in ultrafast field‐emission, particularly sub‐optical‐cycle field emission, based on various nanostructures (e.g., metallic nanotips, carbon nanotubes) is reviewed. A number of promising nanomaterials and possible future research directions are also established. 相似文献
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对氮离子注入掺杂的微波等离子CVD金刚石薄膜进行了场电子发射研究。结果表明,发射具有3特征,即当样品损伤层被击穿、发射体被激活后,稳定的发射建立起来,并表现出优异的发射性能,开启电压低(45V),发射电流大(130mA)。根据电介质的击穿模型和金属/电介质/真空的发射体模型对结果进行了讨论。 相似文献
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Nitrogenated carbon nanotips (NCNTPs) with different structures were synthesized by plasma-enhanced hot filament chemical vapor deposition using methane, hydrogen and nitrogen as the reactive gases. The structures and compositions of the NCNTPs were studied by field emission scanning electron microscopy (FESEM), micro-Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The XPS spectra reveal that nitrogen is incorporated into the carbon nanotips to form the NCNTPs under plasma condition. The Raman spectra and FESEM images show that the NCNTPs are amorphous structure and their morphologies change with the change in deposition conditions, respectively. The electron field emission (EFE) from the NCNTPs was measured and the EFE results indicate that the NCNTPs with the smooth surfaces and high density can emit a current density of 3 × 103 μA/cm2 at an electric field of 7.2 V/μm, which exhibits better EFE characteristic than the NCNTPs with the carbon nanowires on their surfaces due to small amount of oxygen adsorbed on the smooth surfaces of NCNTPs. According to the possible structures of nitrogen in sp2 cluster in rings, the EFE enhancement of the NCNTPs compared with pure carbon nanotips was studied. The high emission current density (3 × 103 μA/cm2) at low field (7.2 V/μm) suggests that the NCNTPs can serve as effective electron emission sources for numerous applications. 相似文献
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A. L. Musatov K. R. Izrael'yants A. V. Krestinin A. V. Raevsky N. A. Kiselev A. B. Ormont V. V. Artemov O. M. Zhigalina 《Fullerenes, Nanotubes and Carbon Nanostructures》2006,14(2):179-185
For carbon layers with very long and sparse nanotubes (nanofilaments) field electron emission at very low average electric field was observed. Field emission current of 10 µA was obtained at the average electric field Eav=0.16 V/µm and the value of the field amplification coefficient β reached 45,000. At high emission currents (exceeding 30-50 µA) one or several luminous nanotubes (nanofilaments) heated by the emission cuurent have been observed in the gap between the sample and the anode. 相似文献
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Synthesis of carbon nanotubes at low temperature by filament assisted atmospheric CVD and their field emission characteristics 总被引:2,自引:0,他引:2
Multiwalled carbon nanotubes (MWNTs) were synthesized using a hot filament assisted chemical vapor deposition (CVD) at the atmospheric pressure at a substrate temperature of 550 °C. The size of nanotubes was controlled by changing the size of catalyst particles. The structure and composition of these nanotubes were investigated using scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. The electron field emission current of MWNTs was also measured. It was found that the nanotubes with smaller the diameter had higher the emission current levels though synthesis conditions except catalyst particles were the same. These as-grown MWNTs had emission current densities of 6.5 mA/cm2 and 2.5 mA/cm2 at 1 V/μm for 5-8 nm and 20 nm size carbon nanotube samples, respectively. The results indicated that the MWNTs synthesized had low emission threshold voltages and high emission current levels that are favorable properties for field emission-based display device applications. 相似文献
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《Journal of Experimental Nanoscience》2013,8(2):126-134
In the present work, freestanding ZnS nanotipped arrays and hollow tubules have been generated using an electrodeposition technique via template synthesis. The structures and morphologies of the arrays and tubules were investigated using X-ray diffraction and scanning electron microscopy, respectively. Electron field emission properties of the ZnS nanotipped arrays and tubules have been studied in a good vacuum condition at room temperature and current–voltage characteristics were found to follow the Fowler–Nordheim theory.It is found that ZnS tubules show good electron field emission properties at low voltage with large field enhancement factor compared to ZnS solid arrays. Optical properties of such synthesised structures were also studied using ultraviolet–visible spectrophotometery. 相似文献