Local Crystallization of ${\rm LaB}_{6}$ Yielding Compact, Strong Thermionic Electron Emission Source

Abstract

Local microheating of amorphous LaB6 film could control the degree of crystallization as determined by spatially resolved Raman spectroscopy and transmission electron microscopy. With full crystallization of the LaB6, we achieved micrometer-sized thermionic electron emission source with the maximum current density of 1.2 A/cm2. The advantage of fabricating a micrometer-sized emitter with high current density enables versatile applications such as compact X-ray or vacuum type terahertz radiation sources. A new structure of micrometer-sized, lateral-type vacuum channel transistor is proposed based on the simulation. The calculated electron travelling time from emitter-to-collector was 8.3 ps at the traveling distance of ~10 μm, meaning that the maximum operation frequency is 120 GHz.