Potential of a cerium hexaboride electron gun as a monochromatic and high current beam via a virtual source mode

Advancements in surface science hinge critically on the evolution of high-performance electron sources, which are essential for achieving the precision level and resolutions required for nanoscale characterization, modification, and fabrication. Cerium hexaboride (CeB6) electron guns, despite being underutilized, stand out for their advantages such as high brightness and operability under high-vacuum environment. This study explores the intrinsic properties and emission conditions of CeB6 electron guns, demonstrating their remarkable performance potential. By carefully controlling the heating temperature and local electric field in a novel virtual source mode, we significantly enhance the electron emission characteristics of CeB6 as a thermal electron source. Operating in the proposed virtual source mode, CeB6 electron guns can reduce chromatic aberrations, offering significant opportunities for high-resolution patterning, spectroscopy, and applications requiring high emission currents. The micrometer-sized electron source exhibits a high angular current density of 48 mA/sr and an energy distribution of 0.32 eV. Additionally, the stability of the virtual source mode was determined to be ± 0.071% at a beam current of 370 nA, a substantial improvement over the ± 0.36% stability value in the crossover mode. With the development of the proposed electron source, new avenues for advanced material characterization, nanoscale fabrication, and precise modifications of material properties will be explored.