Damage to few-layer graphene sheets during electron field emission
Damage to few-layer graphene sheets during electron field emission
复制标题
DOI：
10.1016/j.carbon.2017.07.072
复制
发表时间：
2017-12
期刊：
影响因子：
10.9
通讯作者：
J. Meng;Lisheng Zhang;Yan Fang
中科院分区：
文献类型：
--
作者：
J. Meng;Lisheng Zhang;Yan Fang
石墨烯具有优异的场发射性能，但发射电流呈现不可逆转的下降趋势。这种下降的原因还没有得到明确的研究或彻底的确定，这限制了石墨烯作为场发射体的应用。在这项工作中，首次通过引入板针式装置，在发射电流衰减的同时，观察到了几层石墨烯薄片的损伤。较低的开启电场显示出良好的发射能力。石墨烯薄膜边缘最薄的区域具有高发射效率，是第一个被破坏的区域。因此，由于电流的局部加热效应引起的热助场蒸发，石墨烯薄膜变短，呈现出更厚的锯齿状边缘，导致发射能力下降。与损伤相反，石墨烯薄片的拉曼光谱特征变化不明显，表明剩余的石墨烯薄片保留了石墨烯结构，只是形态发生了变化，使ϕ保持不变。这项工作首次提供了直接和可信的证据，证明发射性能的下降是由于石墨烯薄膜的损伤导致的，这导致了它们的几何形状的变化，并决定了β。
Graphene has demonstrated excellent field emission performance, however, the emitted-current shows irreversible decline. The cause of this decline has not been clearly studied or thoroughly identified, which limits application of graphene as field emitters. In this work, accompanied by the decay of emission currents, the damage to few-layer graphene sheets was observed for the first time by introducing a plate-needle-type setup. The low turn-on field show excellent emission ability. The thinnest regions at the edges of graphene sheets, which have high emission efficiency, are the first to be destroyed. Thus, the graphene sheets become shortened and show thicker serrated edges because of thermally assisted field evaporation induced by the local heating effect of the currents, resulting in the degradation of emission ability. In contrast to the damage, changes in the Raman features of the graphene sheets are not visible, indicating that the graphene structure is retained in the remaining graphene sheets and only the morphology is changed, which renders the ϕ unchanged. This work provides the first direct and credible evidence that the degradation of emission performance is derived from damage to the graphene sheets, which leads to changes in their geometry and determines the β.