Articles you may be interested inEffect of oxygen plasma on field emission characteristics of single-wall carbon nanotubes grown by plasma enhanced chemical vapour deposition system J. Appl. Phys. 115, 084308 (2014); 10.1063/1.4866995Low threshold field emission from high-quality cubic boron nitride films J. Appl. Phys. 111, 093728 (2012); 10.1063/1.4711093Effect of cubic phase evolution on field emission properties of boron nitride island films An individual multiwall carbon nanotube ͑CNT͒ synthesized without a catalyst by an arc discharge method is bonded to a tungsten tip. Field emission characteristics of the individual CNT coated with a boron nitride ͑BN͒ nanofilm are investigated. The BN film is synthesized by plasma-assisted chemical vapor deposition method in which boron trichloride ͑BCl 3 ͒ and nitrogen ͑N 2 ͒ are used as source gases. Deposition of the BN film with a thickness less than 10 nm onto the individual CNT is attempted. Field emission characteristics are measured in the chamber evacuated to 2 ϫ 10 −8 Pa. An anode electrode is set 25 mm away from the CNT sample. The turn-on electric field, designated as an electric field at an emission current of 1.0 nA, is compared between individual CNTs with and without the BN nanofilm. A significant reduction in the turn-on electric field is achieved by coating with the BN nanofilm. The turn-on electric field is estimated to be 1.2ϫ 10 −2 V / m for the uncoated individual CNT sample, and the turn-on electric field is estimated to be 8.2ϫ 10 −3 V / m for the CNT sample coated with BN nanofilm. Moreover, stable operation is demonstrated at an emission current as high as 1 ϫ 10 −5 A.
A point electron source is desired to improve performance of high brightness electron beam instruments. It is valuable to create nano-sized tungsten (W) tip from sharp ordinary polycrystalline W needle. The sharp W needle, which is manufactured by electrochemical etching, has been practically utilized as a cold field emission electron source. A novel method for formation of single crystalline W nanotip on the top of h-BN coated conventional polycrystalline tungsten, by supplying high voltage, has been found. The W nanotip with an apex radius as small as a few times 10 nm would be grown on the top of the polycrystalline W needle. Field emission characteristics of obtained W nanotip are measured, and the field emission microscopic (FEM) and transmission emission microscopic (TEM) images are observed. The emission current from the W nanotip is measured to exceed 0.1 mA. The FEM image shows significant electron emission from the crystallographic facets of the W single crystal. From these results, the present method for formation of the single crystalline W nanotip would be expected as a key technology to realize a point electron source with a nano-sized apex which makes it possible to improve the performance of high brightness electron beam instruments, especially tiny X-ray tubes for medical use, as well as a cantilever of scanning probe microscope.
The application of a wavelength dispersive x-ray spectrometer, instead of the conventional energy dispersive spectrometer, to particle induced x-ray emission analyses of GaAs is reported in this paper. The apparatus and its feasibility are described in detail through measurements of standard samples, Si, Mg, and B in GaAs. The conclusion is that the technique is a good tool for light elements analysis in heavy materials such as GaAs, but proper application of the technique necessitates carefully chosen samples.
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