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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...
Nitrogen-incorporated ultrananocrystalline diamond, (N)UNCD, is an unconventional field emitter that performs in planar thin film configuration and has turn-on fields on the order of 10 V/ m. To shed more light on fundamental field emission properties of (N)UNCD, we have designed and commissioned a field emission microscope (FEM). The microscope can directly image the field emission site distribution...
Nanostructured thermionic energy converters may offer substantial advantages over traditional devices by reducing system complexity and requirements. However, they still face similar fundamental challenges, such as anode collection efficiency and the space charge effect, which have limited their performance to date. Here, we investigate a carbon nanotube-based thermionic converter, demonstrating that...
The cold cathode x-ray source was fabricated by using the point-type CNT film emitter. The CNT x-ray source consists of the CNT point emitter, the metal mesh gate electrode and the tungsten target anode electrode. Those components were mounted in a small vacuum chamber. The fabricated CNT x-ray source shows a high resolution x-ray image at a low anode current and at a low anode voltage compared to...
Robustness of field emitter arrays against high-energy X-ray irradiation was demonstrated. The current-voltage characteristics of the field emitter array were investigated in a vacuum chamber connected to an electron accelerator. The electron beam with an energy of 1 MeV was incident onto a tungsten thin plate to produce X-rays. The field emitter array showed the almost identical current-voltage characteristics...
We fabricated a high performance electron beam for the vacuum electronic devices with carbon nanotube (CNT) cathode. For the vacuum electronic devices application, a structure of cold cathode should be highly adhere on cathode substrate and endure a resistive heating during electron emission. For fabrication of stable electron beam, we optimized the CNT emitters and the triode structure. The structural...
Microstructured silicon carbide field emission arrays has been combined with field electrode or gate acting on arrays of nanotips. Simulation results demonstrate rather high emission current density at relatively low operating voltage on the gate.
Silicon carbide field emission arrays coated with two different type of nanocrystalline diamond thin film: undoped and highly boron-doped are compared. The last one shows two times lower electric field threshold for electron emission.
In this work, we present FEAs based on silicon field emitter tips on top of silicon nanowires with four different device structures: (a) buried tips, (b) buried tips with graphene, (c) released tips, and (d) released tips with graphene. Measured device parameters are used to characterize the performance of the devices. In general, we obtain low turn-on voltages when bFN is low. Additional studies...
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...
We used photolithography to fabricate nanoscale grids in proximity to a metal electrode. Such nanoscale grids can be used to mitigate the space charges in the inter-electrode region of a thermionic converter. The nanoscale dimensions together with low fill factor of the grid led to low electron absorption, which was measured experimentally. We further demonstrated space charge mitigation using such...
Nowadays, the sensitivities of the ionization gauges with carbon nanotube (CNT) cathodes are generally low, which is unfavorable for the measurement of extremely high vacuum (XHV). In order to solve the problems, a spherical oscillator gauge with CNT cathode, which has high gauge sensitivity, is simulated using SIMION 8.0 and experimented preliminarily. The numerical simulation results show that the...
We describe the fabrication process for an anode of a miniaturized transmission electron microscope. The anode consists of a very thin membrane (membrane-anode) that encloses the electron optics microsystem and it is used to separate the high vacuum part from the sample chamber in the microscope. The membrane-anode is made of Si3N4 layer deposited on an oxidized silicon substrate and was fabricated...
For the realization of a miniaturized field emission electron source we tested benzocyclobutene (BCB) as a new spacer material between cathode and anode. We fabricated black silicon emitters and characterized the emission behavior with an integrated 5 μm thin and large-area spacer of BCB. The integrated BCB layer allows the realization of a compact electron source with only two components consisting...
We developed deep UV generation techniques with home-made wide bandgap anode and carbon nanotube (CNT) based cold cathode electron beam (C-beam). The wide bandgap anodes excited with high performance C-beam. The fabrication process for anodes were developed and optimized for high performance deep UV generation. Also, the performance of C-beams optimized. With the optimized C-beam and anode, we could...
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...
Amorphous indium-gallium-zinc-oxide thin film transistor (a-IGZO TFT) was used as active driving device for ZnO nanowire field emitters. The characteristics of ZnO FEAs controlled by a-IGZO TFT were studied. Low driving voltage, precise control and stabilization of field emission current are achieved.
We propose an advanced active current-control (ACC) unit composed of two cascade transistors for extremely stabilizing field emission currents. The upper transistor connected to the cathode modulates high voltages for field emission while the other one regulates emission current stably. Using the ACC unit developed, very stable emission currents were achieved from the fully vacuum-sealed x-ray tube...
Reducing the emission of secondary electrons from anode materials is critical to improved efficiency and increased performance in high power vacuum electronics for defense systems. The focus of this proposed effort is to leverage advances in materials technology, specifically thin films, to reduce secondary electron generation and outgassing from anode surfaces. By using advanced thin film deposition...
Field Emission Pattern Image of Carbon Nanotubes has been captured by using electron beam scanning analyzer. The measurement showed that the Faraday cup scanning method can provide a high resolution field emission sites distribution measurement (the best resolution is up to 0.01mm), which is higher than that using the transparent anode method.
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