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At present, many vacuum devices based on nanotechnology are widely used. The life time of the device depends mainly on the outgassing rate and the seal leak rate of the device. The leak rate is required to be less than 10−14Pam3/s in some application fields of long-life and high reliability devices. To solve this problem, the ultra-high vacuum leak detection apparatus with the lower limit of 10−16...
Ultrafast electron pulses, combined with laser-pump and electron-probe technologies, allow for various forms of ultrafast microscopy and spectroscopy to elucidate otherwise challenging to observe physical and chemical transitions. However, the pursuit of simultaneous ultimate spatial and temporal resolution has been largely subdued by the low monochromaticity of the electron pulses and their poor...
Electron emission induced by picosecond laser from solid surfaces placed under an intense electric field has been modeled. The results show an important difference between the electrons temperature (5500 K) and the phonons temperature (850 K). In these conditions, the Fermi-Dirac distribution depends of the electron temperature, while the thermo-field emission becomes effective for temperatures well...
Hyperspectroscopy consists of spatially-resolved collection of spectra. In order to characterize the performance of electron emitters, in particular thermionic emitters, the thermal characteristics must be known. In this work, we use hyperspectroscopy to map out the blackbody temperature distribution on the surface of an optically-excited source comprised of a carbon nanotube (CNT) forest — a promising...
In this work, we analyze properties of cold field emission from a low-dimensional, paraboloidal emitter tip. We find that the entirety of the emitted current density (ECD) originates from a few high-energy, zero-angular-momentum subbands and from a region on the tip that is highly localized around the apex. In addition, Fowler-Nordheim (FN) plots for such emitters are non-linear and do not serve as...
We reported fabrication and field emission properties of carbon nanotube (CNT) field emitters which indicated the point-type CNT film emitter and line-type CNT film emitter. The CNT film field emitters were made by cutting CNT film using a razor. The CNT film emitters showed good emission properties such as the low turn-on field, the high emission current in a triode configuration. Especially, the...
A transparent cold cathode panel was fabricated and applied in a double-side emitting light source using ZnO nanowire field emitter arrays(FEAs). ITO thin film coating on starting Zn film was adopted to modify the morphology and field-emission properties of ZnO nanowires. The transparent ZnO nanowire cold cathode panel shows more than 84.7% transmission in the visible light region. A fully sealed...
Using the ZnO nanowire emitters with the photoconductor as the anode, the concept of a light-responsive field emission display (FED) was demonstrated. The brightness of display can be automatically increased with the increasing of external light-intensity. Additionally, the photo/dark current ratio can be controllably adjusted by changing the device parameters. The response of conductivity of photoconductor...
We have continued our investigation of the tunneling currents between CNTs dispersed randomly in the 3-dimensional potential of a dielectric medium. In addition to the configurations of CNTs which give a 2 orders of magnitude higher current than the standard tip to tip configuration studied previously we have discovered CNT configurations which do the opposite i.e. give currents which are 2 orders...
Field-emission scanning probe lithography based on a Fowler-Nordheim type electron emission from a nanotip enables cost-effective technology for nanodevices. Thereby, the emitted electrons expose directly a ultrathin resist film (below 50nm). The electron energies are in the range of a few tens of electron volts, which is close to the binding energies of resist molecules. During the patterning process...
Improvement of the electron emission properties of the planar-type electron emission devices based on a graphene-oxide-semiconductor (GOS) structure was achieved by vacuum annealing at 300 oC. Electron emission efficiency of GOS type electron emission devices reached 2.7 % from 0.2 % after vacuum annealing. The work function of graphene electrode was found to decrease 0.26 eV after vacuum annealing...
Needle-like single crystal diamond structures were obtained by combination of the plasma enhanced chemical vapor deposition (CVD) and selective oxidation techniques. Field emission currents and total electron energy distributions were measured for individual diamond needles as functions of extraction voltage and the intensity of the femtosecond laser focused on the needle. Moreover, a new set-up based...
We present experimental results on laser-induced photoemission from nanotips made of different materials, and we compare photoemission from a metal surface (tungsten) to a dielectric (diamond). Ultrashort laser pulses (15–300 fs) are used to trigger electron emission from nanotips with radii < 100nm under a moderate tip bias. We show how different laser parameters as the repetition rate, the mean...
Field emitter is an important cathode to probe atomic structures of large unit-cell crystal samples by electron imaging and diffraction experiments because of the capability to produce high brightness electron beam with a large transverse coherence length. Despite the small energy spread, normally only the near-axis part of the beam is utilized because of the large geometrical angular spread at the...
We report on an extended use of the Fowler-Nordheim plot for energetic evaluation of charge transfers in vacuum electronics. First results explained clearly, the transition from field electron emission to plasma discharge is physically conditioned, especially in the case of higher emission currents.
Vacuum arcing (also known as breakdown), is a major limiting factor in various applications such as particle accelerators, fusion reactors etc. Although it is well-established that vacuum arcs appear after intense Field electron Emission (FE), the physical mechanism that leads from FE to the ignition of plasma is not yet understood. A common hypothesis is that intense FE leads to excessive heating...
Experimental field emission data from large area field emitters (LAFEs) have been analyzed using a “two-class model”, in which some emitters have a field enhancement factor significantly greater than the remainder. Using parameters derived experimentally, corresponding Fowler-Nordheim plots were theoretically predicted and agree adequately with the “kinked” plots observed experimentally. In the analysis...
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