Ultrabright LaB6 nanoneedle field emission electron source with low vacuum compatibility
Mingkai Gou, Shuai Tang, Kai Huang, Haokun Guan, Runze Zhan, Chaolun Liang, Chengcheng Chen, Yan Shen, Shaozhi Deng
Abstract
An electron source with high performance and low vacuum compatibility is urgently in demand for the electron-beam instruments. However, there exists compromise between high brightness, small energy spread, and low vacuum for the commercial electron sources. To overcome this challenge, here we use a self-heating effect to stabilize the single-crystalline LaB6 nanoneedle point field emitter under low vacuum. An ultrahigh reduced brightness of 1012 A/m2/sr/V which is three orders of magnitude higher than commercial W field emitter and with monochromatic energy spread of 0.5 eV were calculated at a large current of 2 μA, showing a stable emission with fluctuation of 3.4%/hour in a low vacuum at 7 × 10−6 Pa which is three orders of magnitude lower than the operating environment of commercial W field emitter. The ultrahigh brightness and small energy spread are attributed to the sharp, robust structure and low work function of LaB6 nanoneedle made by focused ion beam. Field emission electron sources offer high brightness and small energy spread, but their use is limited by ultra-high vacuum requirements. Here, a focused ion beam-fabricated LaB6 nanoneedle is presented that achieves ultrahigh brightness and stable low-vacuum emission via self-heating