边界修饰醚基的锯齿形石墨烯纳米条带的场发射的第一性原理研究

采用一种基于密度泛函理论计算的自洽方法研究了边界修饰有C-O-C醚基的锯齿形石墨烯纳米条带(包括边界有连续的醚基ZGNR-CE和50%覆盖度的醚基ZGNR-AE)的电子场发射特性. 模拟结果显示两种纳米条带的场发射主要由布里渊区中心且靠近费米面的电子态所决定. 因为具有较低的功函数，ZGNR-CE条带能产生比未修饰的重构锯齿形石墨烯纳米条带强很多的场发射电流；而ZGNR-AE条带有着几乎完全自旋极化的场发射电流，尽管电流不够强. 另外在较低的外电场下，单轴方向的外加应变能有效调控它们的场发射电流，但ZGNR-AE条带的高自旋极化保持不变. 通过分析这些条带的功函数、能带结构以及结合边界电偶极模型，揭示了相关机制.

First-Principles Study of Field Emission from Zigzag Graphene Nanoribbons Terminated with Ether Groups

Field emission properties of zigzag graphene nanoribbons terminated with C-O-C ether groups (including cyclic and alternative ether groups at edge, denoted as ZGNR-CE and ZGNR-AE) are studied by adopting a self-consistent method based on density functional theory calculation. The results show that the field emissions of these two nanoribbons are dominated by states around Brillouin zone center and close to Fermi level. Because of lower work function, the ZGNR-CE can produce much stronger emission current than recon-structed zigzag graphene nanoribbon. The ZGNR-AE has nearly completely spin-polarized emission current, although its emission current is not strong enough. It is also found that under the lower E-field, the uniaxial strain can effectively modulate their emission currents but the spin polarization of ZGNR-AE keeps unchanged with the varied strain. The under-lying mechanisms are revealed by combining the analyses of their work functions and bandstructures with edge dipole model.