• 文献标题:   Flat-Lens Focusing of Electron Beams in Graphene
  • 文献类型:   Article
  • 作  者:   TANG Y, CAO XY, GUO R, ZHANG YY, CHE ZY, YANNICK FT, ZHANG WP, DU JJ
  • 作者关键词:  
  • 出版物名称:   SCIENTIFIC REPORTS
  • ISSN:   2045-2322
  • 通讯作者地址:   East China Normal Univ
  • 被引频次:   3
  • DOI:   10.1038/srep33522
  • 出版年:   2016

▎ 摘  要

Coupling electron beams carrying information into electronic units is fundamental in microelectronics. This requires precision manipulation of electron beams through a coupler with a good focusing ability. In graphene, the focusing of wide electron beams has been successfully demonstrated by a circular p-n junction. However, it is not favorable for information coupling since the focal length is so small that the focal spot locates inside the circular gated region, rather than in the background region. Here, we demonstrate that an array of gate-defined quantum dots, which has gradually changing lattice spacing in the direction transverse to propagation, can focus electrons outside itself, providing a possibility to make a coupler in graphene. The focusing effect can be understood as due to the gradient change of effective refractive indices, which are defined by the local energy band in a periodic potential. The strong focusing can be achieved by suitably choosing the lattice gradient and the layer number in the incident direction, offering an effective solution to precision manipulation of electron beams with wide electron energy range and high angular tolerance.