Yunkang Cui

ZnO Electron Field Emitters on Three-Dimensional Patterned Carbon Nanotube Framework

A three-dimensional patterned CNT framework was prepared in a thermal chemical vapor deposition system. ZnO nanoneedles with different areal density were subsequently grown on it via hydrothermal method. By combining the advantages of high aspect ratio, more effective emission sites with minimized screen effect and good Ohmic contact between ZnO nanoneedles and CNT framework, the ZnO/CNT hierarchical nanostructures with medium areal density exhibit a favorable FE performance which makes it promising candidate for cold cathode nanomaterials.

Study of a micro chamber quadrupole mass spectrometer

Copyright @ 2008 American Vacuum Society / American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Journal of Vacuum Science and Technology Part A: International Journal Devoted to Vacuum, Surfaces, and Films, 26(2), Article number 239 and may be found at http://scitation.aip.org/content/avs/journal/jvsta/26/2/10.1116/1.2827512.

Residual gas analysis based on carbon nanotube field emission display

The authors measured the residual gas spectrum of a field emission display (FED) with carbon nanotube (CNT) emitters and found that the main residual gases inside a sealed CNT FED, containing an evaporated Ba getter, are H2, CH4, CO, Ar, and CO2, all of which are typical residual gases of electronic vacuum tubes. Additionally they also measured the electron stimulated desorption of gases by operating their field emission devices.

Hybrid single/poly-crystalline ZnO nanoawl arrays: facile synthesis and enhanced field emission properties

Arrays of hybrid single/poly-crystalline ZnO nanoawls (HSP-ZNAs) composed of single-crystalline ZnO nanorod (ZNR) holders and poly-crystalline nanoneedles were for the first time fabricated via a facile two-step synthesis strategy that was based on firstly an aqueous electrodeposition and secondly an aqueous chemical growth (ACG). The two-step synthesis strategy not only can ensure reliable electrical contact between the ZNR holders and the substrates, but also can afford control over the crystal structure and aspect ratio of the nanoneedles. The as-grown HSP-ZNA arrays exhibited markedly enhanced field emission (FE) current at lower electric fields compared with the whole single-crystalline ZNA arrays or ZNR arrays without nanoneedles. The improvement could be attributed to more emission sites from the tips of poly-crystalline nanoneedles of the HSP-ZNAs. Our results demonstrate the HSP-ZNA arrays one of the promising candidates for FE devices, and also provide a new paradigm for synthesizing novel hybrid single/poly-crystalline nanostructures that could find many potential applications in electronics and optoelectronics.

Stable field emission lamps based on well-aligned BaO nanowires

Well-aligned BaO nanowires were synthesized on ITO glass substrates by a hydrothermal process. The morphology and composition of the BaO nanowires were characterized by field emission scanning electron microscopy, high resolution transmission electron microscopy, selected area electron diffraction, X-ray diffraction, and energy dispersive X-ray spectroscopy. The results confirmed that BaO nanowires had single crystalline cubic structures and grew along the [111] direction. The well-aligned BaO nanowires show superior field emission properties, and exhibited a low turn-on field (∼0.9 V μm−1), a low threshold field (∼3.59 V μm−1), a high field enhancement factor (β = 2463), and a good stability of the emission current. The field emission lamps fabricated by using the BaO nanowires as emitters display uniform and bright emission patterns under the diode mode. These results demonstrate that such BaO nanowires are promising for application in practical flat panel displays.

Fabrication and Characterization of a Planar Triode Structure Based on Honeycomb Carbon Nanotubes

We report a planar triode with metal-gate-free electrode based on carbon nanotubes. Excellent field emission properties with 1.4 mA/cm2 at the gate voltage of 32 V are obtained. A turn-off phenomenon is observed when the gate voltage decreases to 0 V. The field emission at 1.2 mA/cm2 is recorded for 20 h with the fluctuation of the emission current . The results would be of significance to the development of field emission triode structure in the future.

Evaporation of Tetrapod ZnO Nanostructures and Its Influence on the Field-Emission Performance

The ZnO cathode is a promising electron source due to its excellent field-emission performance. In this letter, we investigate the evaporation characteristics of the field emitters in a screen-printed ZnO cathode by a quadrupole mass spectrometer, energy-dispersive X-ray, and scanning electron microscopy. As the experiments show, the oxygen and zinc start to be evaporated if the temperature is higher than 1273 K. The quantity of evaporative materials increases with the increment of temperature, and the quantity of evaporated oxygen is much larger than that of zinc. The evaporations of oxygen and zinc have considerable effects on the field-emission properties of the ZnO cathode, particularly the turn-on field, the threshold electric field, and the emission current density. Therefore, the evaporation of field emitters is an important factor for the stability of the field-emission current.

P1–39: Large current emission from CNTs synthesized by a local heating CVD method

A local heating chemical vapor deposition method is used to synthesize carbon nanotubes onto a metal substrate. Compared with normal thermal chemical vapor deposition, this method can provide faster growth rate, more nodes can be formed onto the carbon nanotubes, and emission sites can be increased largely. A maximum current over 100mA was obtained from carbon nanotubes emitter layer with emission area is about 0.7cm2. This method provides an effective way to fabricate carbon nanotubes into a vacuum electronic device to realize large current emission from a cold cathode instead of a thermionic cathode.

Surface modification of CNT-cathodes by an acid-erosion process

We describe the preparation and properties of a carbon nanotube (CNT) paste for screen-printing CNT-cathodes. Inorganic binders have been added to the paste to improve the adhesion to the substrate and Zn powder has been added to reduce the loss of CNTs during thermal processing. An efficient method called the acid-erosion process has been introduced to improve the surface morphology of the CNT-cathodes made with the paste. The surface modification was verified with electron microscopic analyses, while the improvements in field emission and emission uniformity were quantified in a diode structure.

High performance field emission of silicon carbide nanowires and their applications in flexible field emission displays

In this paper, a facile method to fabricate the flexible field emission devices (FEDs) based on SiC nanostructure emitters by a thermal evaporation method has been demonstrated. The composition characteristics of SiC nanowires was characterized by X-ray diffraction (XRD), selected area electron diffraction (SAED) and energy dispersive X-ray spectrometer (EDX), while the morphology was revealed by field emission scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The results showed that the SiC nanowires grew along the [111] direction with the diameter of ∼110 nm and length of∼30 μm. The flexible FEDs have been fabricated by transferring and screen-printing the SiC nanowires onto the flexible substrates exhibited excellent field emission properties, such as the low turn-on field (∼0.95 V/μm) and threshold field (∼3.26 V/μm), and the high field enhancement factor (β=4670). It is worth noting the current density degradation can be controlled lower than 2% per hour during the stability tests. In addition, the flexible FEDs based on SiC nanowire emitters exhibit uniform bright emission modes under bending test conditions. As a result, this strategy is very useful for its potential application in the commercial flexible FEDs.In this paper, a facile method to fabricate the flexible field emission devices (FEDs) based on SiC nanostructure emitters by a thermal evaporation method has been demonstrated. The composition characteristics of SiC nanowires was characterized by X-ray diffraction (XRD), selected area electron diffraction (SAED) and energy dispersive X-ray spectrometer (EDX), while the morphology was revealed by field emission scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The results showed that the SiC nanowires grew along the [111] direction with the diameter of ∼110 nm and length of∼30 μm. The flexible FEDs have been fabricated by transferring and screen-printing the SiC nanowires onto the flexible substrates exhibited excellent field emission properties, such as the low turn-on field (∼0.95 V/μm) and threshold field (∼3.26 V/μm), and the high field enhancement factor (β=4670). It is worth noting the current density degradation can be controlled lower than 2% per hour...