An in situ characterization technique for electron emission behavior under a photo-electric-common- excitation field: study on the vertical few-layer graphene individuals
An in situ characterization technique for electron emission behavior under a photo-electric-common- excitation field: study on the vertical few-layer graphene individuals
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光电共激发场下电子发射行为的原位表征技术：垂直少层石墨烯个体的研究
DOI：
10.1088/1361-6528/ab3609
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发表时间：
2019-11-01
期刊：
影响因子：
3.5
通讯作者：
Deng, Shaozhi
中科院分区：
文献类型：
--
作者：
Shen, Yan;Xing, Yang;Deng, Shaozhi
对个体的原位表征为探索纳米尺度材料的动态行为和基础物理提供了有效的方法，这有利于实际应用。在真空微纳电子学领域，现有的原位技术可以在单一激发源驱动的电子发射过程中获得材料的结构、形貌和成分等信息。然而，当两个或多个激励源共同作用于发射器时，相关过程和机制变得更加复杂。在本文中，我们提出了一种原位纳米表征技术来触发和记录光电共激发多重物理场下的电子发射行为。具体来说，我们研究了激光加静电驱动场下单个垂直少层石墨烯（vFLG）发射器的原位电子发射。电子从 vFLG 的发射边缘被驱出，在外部静电场与 785 nm 连续波激光触发光场耦合下原位运行。入射光已被证明可以显着改善石墨烯的电子发射性能，其开启电压明显降低，发射电流提高了35倍，光响应开关比高达5。更重要的是，在实际电子发射过程中，通过SEM观察和拉曼光谱等一系列原位表征来研究发射体的结构、成分甚至实时拉曼频率变化。这些信息可以进一步揭示电子发射特性的关键因素，例如场增强、功函数和实时表面温度。此后，本研究中的vFLG发射机制被半定量地证明为光子辅助热增强场发射和光场发射两个并行过程。
The in situ characterization on the individuals offers an effective way to explore the dynamic behaviors and underlying physics of materials at the nanoscale, and this is of benefit for actual applications. In the field of vacuum micro-nano electronics, the existing in situ techniques can obtain the material information such as structure, morphology and composition in the process of electron emission driven by a single source of excitation. However, the relevant process and mechanism become more complicated when two or more excitation sources are commonly acted on the emitters. In this paper, we present an in situ nano characterization technique to trigger and record the electron emission behavior under the photo-electric-common-excitation multiple physical fields. Specifically, we probed into the in situ electron emission from an individual vertical few-layer graphene (vFLG) emitter under a laser-plus-electrostatic driving field. Electrons were driven out from the vFLG's emission edge, operated in situ under an external electrostatic field coupled with a 785 nm continuous-wave laser-triggered optical field. The incident light has been demonstrated to significantly improve the electron emission properties of graphene, which were recorded as an obvious decrease of the turn-on voltage, a higher emission current by factor of 35, as well as a photo-response on-off ratio as high as 5. More importantly, during their actual electron emission process, a series of in situ characterizations such as SEM observation and Raman spectra were used to study the structure, composition and even real-time Raman frequency changes of the emitters. These information can further reveal the key factors for the electron emission properties, such as field enhancement, work function and real-time surface temperature. Thereafter, the emission mechanism of vFLG in this study has been semi-quantitatively demonstrated to be the two concurrent processes of photon-assisted thermal enhanced field emission and photo field emission.