title: An ultrabright and monochromatic electron point source made of a LaB6 nanowire.
abstract: Electron sources in the form of one-dimensional nanotubes and nanowires are an essential tool for investigations in a variety of fields, such as X-ray computed tomography, flexible displays, chemical sensors and electron optics applications. However, field emission instability and the need to work under high-vacuum or high-temperature conditions have imposed stringent requirements that are currently limiting the range of application of electron sources. Here we report the fabrication of a LaB6 nanowire with only a few La atoms bonded on the tip that emits collimated electrons from a single point with high monochromaticity. The nanostructured tip has a low work function of 2.07 eV (lower than that of Cs) while remaining chemically inert, two properties usually regarded as mutually exclusive. Installed in a scanning electron microscope (SEM) field emission gun, our tip shows a current density gain that is about 1,000 times greater than that achievable with W(310) tips, and no emission decay for tens of hours of operation. Using this new SEM, we acquired very low-noise, high-resolution images together with rapid chemical compositional mapping using a tip operated at room temperature and at 10-times higher residual gas pressure than that required for W tips.
authors.affiliation: National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan.
authors.forename: Han
authors.initials: H
authors.lastname: Zhang
authors.affiliation: National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan.|Graduate School of Pure and Applied Science, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan.
authors.forename: Jie
authors.initials: J
authors.lastname: Tang
authors.affiliation: National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan.
authors.forename: Jinshi
authors.initials: J
authors.lastname: Yuan
authors.affiliation: National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Yamauchi
authors.affiliation: National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan.
authors.forename: Taku T
authors.initials: TT
authors.lastname: Suzuki
authors.affiliation: National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan.
authors.forename: Norio
authors.initials: N
authors.lastname: Shinya
authors.affiliation: National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan.
authors.forename: Kiyomi
authors.initials: K
authors.lastname: Nakajima
authors.affiliation: Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3255, USA.
authors.forename: Lu-Chang
authors.initials: LC
authors.lastname: Qin