新型同轴电极结构碳纳米管场发射电离计

本文以碳纳米管(CNT)作为阴极电子源设计一种新型的冷阴极电离真空计结构,结构包括场发射电子源、阳极和离子收集极,阳极和离子收集极为同轴圆环结构。利用热化学气相沉积法在金属基底上直接生长碳纳米管,分别制备了4mm×5mm矩形和直径0.1mm圆形两种阴极发射面。碳纳米管阴极具有优异的场发射性能,开启电场1.70 V/μm。在氮气环境下,分别对不同阴极真空电离计结构的真空测量性能进行了研究,真空计在10-7到10-3Pa区间归一化电流(Ii/Ia)与压强表现出良好的线性关系,矩形和圆形发射面阴极对应的真空计其测量灵敏度分别是3.1×10-2Pa-1和1.3×10-2Pa-1。     

超高/极高真空测量发展综述

本文回顾了近50多年来在超高/极高真空测量方面所取得的重要进展.内容包括热阴极电离规和冷阴极电离规的研究进展、新型室温电子源(如Spindt阴极和碳纳米管场发射阴极)和真空的激光电离测量技术在超高/极高真空测量中的应用、小型化超高/极高真空电离规的发展以及我国在超高/极高真空测量方面的研究进展等,从中可对超高/极高真空测量的发展历史和现状有一个完整的了解.     

碳纳米管场发射阴极制备及其应用研究

碳纳米管(Carbon nanotube, CNT)薄膜可作为场发射阴极材料,具有常温下工作、物理化学性能稳定、响应时间快等一系列优点,在各类电真空器件中具有潜在的应用价值。本文重点综述了兰州空间技术物理研究所近年来开展的碳纳米管阴极制备及其应用研究进展,总结了CVD法直接生长法制备不同微观形貌的碳纳米管薄膜的实验方法,分析了不同碳纳米管阴极的场发射特性,介绍了其在超高真空测量和空间电推进中的应用现状及最新进展。     

镍—63——真空电子器件中新的预电离源

叙述了低能电子源的特点，比较了＾６３Ｎｉ，＾３Ｈ和＾５５Ｆｅ低能β源的特性，介绍了６５Ｎｉ放射源的制备方法，讨论了＾６５Ｎｉ用作真空电子器件中预电离源的优点，列举了＾６５Ｎｉ源在真空电子器件中的多种应用。     

碳纳米管复合材料场发射性能研究现状

碳纳米管具有管径小、长径比高的结构以及物理化学性能稳定等优良特性,被认为是真空冷阴极场发射电子源和场发射平板显示理想的阴极材料。加之碳纳米管兼具有机械强度高、韧性好等出众的力学性能,使其成为复合材料的理想添加相,将其与其他材料复合,可以制备出具有更加出众性能的复合材料。近年来有关碳纳米管及其复合材料场发射研究已成为一个备受关注的热点。概述了阴极场发射理论以及与碳纳米管场发射相关的几种场发射物理机制,介绍了碳纳米管复合场发射阴极的研究现状及制备方法,最后对碳纳米管复合阴极场发射的发展前景进行了展望。     

碳纳米管的制备、表征及其在电子领域中的应用

碳纳米管的独特结构使它具有奇特的性质和广阔的应用前景。本文介绍了碳纳米管的结构和性质,对碳纳米管的制备现状、表征及其在电子领域的应用做了详细的回顾。     

镍-63——真空电子器件中新的预电离源

叙述了低能电子源 (β源 )的特点 ,比较了6 3Ni,3H和55Fe低能 β源的特性 ,介绍了6 3Ni放射源的制备方法 ,讨论了6 3Ni用作真空电子器件中预电离源的优点 ,列举了6 3Ni放射源在真空电子器件中的多种应用     

碳纳米管基电子皮肤研究综述

电子皮肤是一种能感知外部刺激并将其转化为相应电信号的柔性电子器件。本文介绍了采用碳纳米管制备电阻式和电容式电子皮肤的作用机理、制备方法、相关特性，结合不同的应用场景说明其发展空间，总结了碳纳米管基电子皮肤发展过程中存在的问题，并对其今后发展进行展望。     

场发射冷阴极电离规的研究进展

碳纳米管冷阴极具有优异的场致电子发射特性,在电子源应用方面具有很好的前景,被认为是很有希望取代热阴极的材料之一。本文回顾了20多年来场发射冷阴极电离规的发展。内容包括微尖型场发射阴极电离规和碳纳米管场发射阴极电离规的发展,从中可以看出场发射电离规的现状和发展趋势。最后对碳纳米管超高/极高真空电离规的发展进行了展望。     

基于CVD直接生长法的碳纳米管场发射阴极

碳纳米管(CNT)场发射阴极具有启动快、分辨率高、寿命长、功耗小等优点,在多种真空电子设备与器件上,包括平板显示器、真空测量、微波管、X射线管等得到了应用。本文讨论了碳纳米管阴极的主要制备方法以及存在的问题,介绍了基于化学气相沉积法和阳极化工艺、在含催化金属基底直接制备碳纳米管冷阴极所具有强附着力特点,以及应用在X射线管等强流真空电子器件上的优势。文章介绍了在不锈钢基底直接生长CNT阴极的场发射性能,其开启电场为1.46 V/μm。与常规催化金属镀膜层上生长的CNT阴极相比,大电流发射与稳定性显著提高。金属基底阳极化工艺显著改善碳纳米管结构与场发射性能。直径2 cm的不锈钢基底上生长的CNT具有晶体性好、分布均匀等特点,场发射性能提高。在镍基底上生长的CNT阴极电流密度可以达到500 mA/cm~2以上。     

电离规的新进展

介绍了传统热阴极电离规和冷阴极电离规的发展历程和研究现状、新型场发射阴极(微尖型阴极和碳纳米管阴极)在电离规中的应用、小型化电离规的发展和国内在超高/极高真空电离规研究方面取得的成果和现状。重点回顾了碳纳米管阴极电离规和小型化电离规在近年来取得的重大成就。由于碳纳米管具有长径比大、曲率半径小、机械特性强、导电性好和优异的场发射特性,使得其作为电离规阴极有望解决传统冷阴极电离规在低压下不能放电的困难和传统热阴极电离规的热出气效应,从而为极高真空测量提供一种解决途径。     

Improvement of emission reliability of carbon nanotube emitters by electrical conditioning

We have investigated the effect of electrical aging to improve emission reliability of carbon nanotube (CNT) emitter. The CNT emitters were prepared by the screen-printing of the CNT paste. The electrical aging treatment was carried out in a high vacuum chamber by applying the pulsed dc voltage. The field emission measurements and lifetime tests were performed on the CNT emitters depending on the electrical aging time and current density. After the electrical aging treatment, emission properties of CNT emitter were suppressed but the half lifetime was dramatically improved.     

Growth of carbon nanotube field emitters on single strand carbon fiber: a linear electron source

The multi-stage effect has been revisited through growing carbon nanotube field emitters on single strand carbon fiber with a thickness of 11 μm. A prepared linear electron source exhibits a turn-on field as low as 0.4 V μm(-1) and an extremely high field enhancement factor of 19,300, when compared with those results from reference nanotube emitters grown on flat silicone wafer; 3.0 V μm(-1) and 2500, respectively. In addition, we introduce a novel method to grow nanotubes uniformly around the circumference of carbon fibers by using direct resistive heating on the continuously feeding carbon threads. These results open up not only a new path for synthesizing nanocomposites, but also offer an excellent linear electron source for special applications such as backlight units for liquid crystal displays and multi-array x-ray sources.     

Enhanced Field Emission of WS2 Nanotubes

Results on electron field emission from free standing tungsten disulfide (WS₂) nanotubes (NTs) are presented. Experiments show that the NTs protruding on top of microstructures are efficient cold emitters with turn‐on fields as low as 1 V/μm and field enhancement of few thousands. Furthermore, the emission current shows remarkable stability over more than eighteen hours of continuous operation. Such performance and long‐term stability of the WS₂ cathodes is comparable to that reported for optimized carbon nanotube (CNTs) based emitters. Besides this, it is found that the WS₂ cathodes prepared are less sensitive than CNTs in chemical reactive ambients. The high field enhancement and superior reliability achieved indicates a potential for vacuum nanoelectronics and flat panel display applications.     

Carbon nanotube field emitters for planar emission vacuum micro-and nanoelectronics

The design and manufacturing technology of carbon nanotube field emitters for novel devices of planar emission vacuum micro-and nanoelectronics are described. Prototypes of diode structures with such emitters are obtained in which the threshold field strength amounts to ～2 V/μm and the direct to reverse current ratio exceeds 10⁵. The obtained small scatter of characteristics points to the possibility of creating integrated circuits possessing high operation speed and a working temperature range expanded from ?60 to +30°C.     

Carbon nanotube electron sources and applications

In this review we give an overview of the present status of research on carbon nanotube (CNT) field emitters and their applications. Several different construction principles of field-emission devices with CNTs are summarized. The emission mechanism is introduced and a detailed overview is given of the measured emission properties and related topics of CNT electron sources. We give also several examples of field-emission devices with CNT electron emitters that are presently being investigated in the academic world as well as in industry. Carbon nanotube electron sources clearly have interesting properties, such as low voltage operation, good stability, long lifetime and high brightness. The most promising applications are the field-emission display and high-resolution electron-beam instruments. But several hurdles remain, such as the manufacture of an electron source or an array of electron sources with exactly the desired properties in a reproducible manner.     

Novel method to produce single-walled carbon nanotube films and their thermal and electrical properties

Single-walled carbon nanotube films are promising candidates for applications requiring transparent conductors due to their low sheet resistance and high transparency in the visible region. Vacuum filtration is a common and easy to implement technique to produce such films but it is complicated by the need to transfer the films to desired substrates. Here we report conditions under which single-walled carbon nanotube films produced by vacuum filtration detach from the filter membrane upon submersion into water, providing a facile method to transfer filtration-produced nanotube films to desired substrates. Sheet resistance and transparency measurements show that these films are competitive with other high conductivity films made through more cumbersome procedures. Films post-treated with nitric acid or made with acid pre-treated nanotubes have superior performance to those made with high-purity nanotubes without any acid treatment. Thermal imaging by scanning thermal microscopy indicates that heat dissipation by the film is comparable to that of a glass substrate.     

Shrinking a carbon nanotube

We report a method to controllably alter the diameter of an individual carbon nanotube. The combination of defect formation via electron irradiation and simultaneous resistive heating and electromigration in vacuum causes the nanotube to continuously transform into a high-quality nanotube of successively smaller diameter, as observed by transmission electron microscopy. The process can be halted at any diameter. Electronic transport measurements performed in situ reveal a striking dependence of conductance on nanotube geometry. As the diameter of the nanotube is reduced to near zero into the carbon chain regime, we observe negative differential resistance.     

纳米碳管阵列

在概括纳米碳管阵列特异的场发射效应及在场发射器方面应用前景的基础上，介绍了合成纳米碳管阵列的研究历程以及化学气相沉积法在纳米碳管阵列合成方面的重要意义，就当前纳米碳管阵列的快速合成与低温合成两个发展方向进行了概述，并指出等离子体化学气相沉积法能有效地用于纳米碳管阵列的低温合成。     

Efficient fabrication of carbon nanotube micro tip arrays by tailoring cross-stacked carbon nanotube sheets

Carbon nanotube (CNT) micro tip arrays with hairpin structures on patterned silicon wafers were efficiently fabricated by tailoring the cross-stacked CNT sheet with laser. A blade-like structure was formed at the laser-cut edges of the CNT sheet. CNT field emitters, pulled out from the end of the hairpin by an adhesive tape, can provide 150 μA intrinsic emission currents with low beam noise. The nice field emission is ascribed to the Joule-heating-induced desorption of the emitter surface by the hairpin structure, the high temperature annealing effect, and the surface morphology. The CNT emitters with hairpin structures will greatly promote the applications of CNTs in vacuum electronic devices and hold the promises to be used as the hot tips for thermochemical nanolithography. More CNT-based structures and devices can be fabricated on a large scale by this versatile method.