场电子发射
材料科学
纳米线
共发射极
光电子学
准直器
光学
阴极射线
准直光
电子
电子枪
电子束诱导沉积
扫描透射电子显微镜
纳米技术
透射电子显微镜
激光器
物理
量子力学
作者
Han Zhang,Yu Jimbo,Akira Niwata,Akihiro Ikeda,Akira Yasuhara,Ovidiu Cretu,Koji Kimoto,Takeshi Kasaya,Hideki T. Miyazaki,Naohito Tsujii,Hongxin Wang,Yasushi Yamauchi,Daisuke Fujita,Shinichi Kitamura,Hironobu Manabe
标识
DOI:10.1038/s41565-021-00999-w
摘要
The size tunability and chemical versatility of nanostructures enable electron sources of high brightness and temporal coherence, both of which are important characteristics for high-resolution electron microscopy1-3. Despite intensive research efforts in the field, so far, only conventional field emitters based on a bulk tungsten (W) needle have been able to yield atomic-resolution images. The absence of viable alternatives is in part caused by insufficient fabrication precision for nanostructured sources, which require an alignment precision of subdegree angular deviation of a nanometre-sized emission area with the macroscopic emitter axis4. To overcome this challenge, in this work we micro-engineered a LaB6 nanowire-based electron source that emitted a highly collimated electron beam with good lateral and angular alignment. We integrated a passive collimator structure into the support needle tip for the LaB6 nanowire emitter. The collimator formed an axially symmetric electric field around the emission tip of the nanowire. Furthermore, by means of micromanipulation, the support needle tip was bent to align the emitted electron beam with the emitter axis. After installation in an aberration-corrected transmission electron microscope, we characterized the performance of the electron source in a vacuum of 10-8 Pa and achieved atomic resolution in both broad-beam and probe-forming modes at 60 kV beam energy. The natural, unmonochromated 0.20 eV electron energy loss spectroscopy resolution, 20% probe-forming efficiency and 0.4% probe current peak-to-peak noise ratio paired with modest vacuum requirements make the LaB6 nanowire-based electron source an attractive alternative to the standard W-based sources for low-cost electron beam instruments.
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