A stable LaB₆ nanoneedle field-emission point electron source

Abstract

Electric field-emission from a material of low work function has long been sought as an ideal point electron source to generate a coherent electron beam with high brightness, long service...

Effects of low work-function lanthanum oxides on stable electron field emissions from nanoscale emitters

“…[80][81][82][83][84][85] When the crystal is heated in an oxygen atmosphere to around 500-700 C, the surface starts to be oxidized to yield LaO, La 2 O 3 , B 2 O 3 , LaBO 3 , LaB 3 O 6 , and La 3 BO 6 on the macroscopic scale. 69,86 However, in our experimental conditions, 25 the LaB 6 tip was heated for cleaning in an ultrahigh vacuum, where the desorption processes are as signicant as the oxidation processes. The oxide layers would then be limited to several atomic layers.…”

“…Currently, W is used for the emitter tip of CFE electron guns because it can be processed to dimensions less than 100 nm, which is necessary to create a high electric field (>10 9 V m −1 ) and produce a fairly constant emission current. Many studies have been conducted to find electron source materials with superior emission properties, for example, single-atom tips, 4–6 carbon nanotubes, 7–9 and etched sharp tips of borides, 10–26 carbides, 27–39 and nitrides. 40–46…”

“…24 Furthermore, a LaB 6 nanoneedle created by focused ion beam (FIB) milling demonstrated a higher degree of stability than nanowires and greatly exceeded the performance of the W emitter. 25 The LaB 6 nanoneedle emitter was assembled in a TEM and was capable of long-term stable (<1%/100 h) atomic imaging, which has never been achieved by other CFE electron sources. 26…”

“…We conceived this idea after noticing that the energy-dispersive X-ray spectroscopy (EDS) image of the nanoneedle tip appeared to show a reduction of boron atoms on the surface layers. 25…”

Stable Field Emission from Vertically Oriented SiC Nanoarrays

“…Typical SiC 1D nanostructures, including nanowires [13], nanobelts [7], nanorods [14], and nanoneedles [15], have been realized via a variety of different fabrication methods [4,5,16], which are broadly classified, either via direct synthesis from carbon/silicon sources or via the processing of SiC substrates [8,17]. Although the SiC 1D nanostructures fabricated in these ways have showed excellent FE properties [8,[18][19][20], most are produced in relatively harsh synthesis environments, often requiring very high, CMOS-incompatible processing temperatures and toxic gaseous precursors.…”