Susi Toma, Kotakoski Jani, Kepaptsoglou Demie, Mangler Clemens, Lovejoy Tracy C, Krivanek Ondrej L, Zan Recep, Bangert Ursel, Ayala Paola, Meyer Jannik C, Ramasse Quentin
Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria.
Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria and Department of Physics, University of Helsinki, P.O. Box 43, FI-00014 Helsinki, Finland.
Phys Rev Lett. 2014 Sep 12;113(11):115501. doi: 10.1103/PhysRevLett.113.115501. Epub 2014 Sep 11.
We demonstrate that 60-keV electron irradiation drives the diffusion of threefold-coordinated Si dopants in graphene by one lattice site at a time. First principles simulations reveal that each step is caused by an electron impact on a C atom next to the dopant. Although the atomic motion happens below our experimental time resolution, stochastic analysis of 38 such lattice jumps reveals a probability for their occurrence in a good agreement with the simulations. Conversions from three- to fourfold coordinated dopant structures and the subsequent reverse process are significantly less likely than the direct bond inversion. Our results thus provide a model of nondestructive and atomically precise structural modification and detection for two-dimensional materials.
我们证明，60千电子伏特的电子辐照驱动石墨烯中三配位硅掺杂剂每次以一个晶格位点的方式扩散。第一性原理模拟表明，每一步都是由电子撞击掺杂剂旁边的碳原子引起的。尽管原子运动发生在我们的实验时间分辨率以下，但对38次这样的晶格跳跃进行随机分析发现，它们出现的概率与模拟结果高度吻合。从三配位到四配位掺杂剂结构的转变以及随后的逆过程比直接键反转的可能性要小得多。因此，我们的结果为二维材料提供了一种无损且原子精确的结构修饰和检测模型。
