抄録
Lanthanum hexaboride (LaB6) single crystals have been used as thermionic source in high resolution electron microscopes for over 50 years. LaB6 nanowires have great potential to be used as field emission electron point source, which offers larger brightness than thermionic source. We have developed a chemical vapor deposition process to synthesize LaB6 nanowires on Si substrate with a yield rate of 0.5 mg/cm2. Epitaxial growth of vertically aligned LaB6 nanowires has also been successfully realized on LaB6 films. By using an electrostatic attaching method followed by focused ion beam welding, we successfully fabricated single LaB6 nanowire field emitters. Field emission I-V curve measurement has been carried using a home-built 2010F HRTEM field emission in-situ holder. Extrapolated data shows that the nanowire field emitter has a low work function value of 2.3 e V and it generates an emission current over 20 micro A and an emission current density in the order of 10^8 A/cm2 at a low extraction voltage below 300V.
