论文标题
通过钙和镁插入缓冲层-SIC（0001）界面通过插入钙的独立n掺杂石墨烯
Freestanding n-Doped Graphene via Intercalation of Calcium and Magnesium into the Buffer Layer - SiC(0001) Interface
论文作者
论文摘要
已经对SIC（0001）在CA上的外延石墨烯的插入已经进行了广泛的研究，但正是CA所在的位置仍然难以捉摸。此外，尚未报道MG在SIC（0001）上外延石墨烯下方的MG插入。在这里，我们使用低能电子衍射，X射线光电子光谱，次级电子截止光发射以及扫描隧道显微镜来阐明6H-SIC上的CA-和MG间缩合外皮石墨烯的物理和电子结构（0001）。我们发现CA在缓冲层下方的插入量并键入SI-termiss SIC表面，从而打破了缓冲层的C-SI键，即“自由主义”缓冲层以形成CA交换的准脉冲抗抗抗抑郁烯双层石墨烯（CA-QFSBLG）。在SIC（0001）上，在SIC表面下有序的MG终止重建和与Si-termisted SIC表面的MG键相似，在SIC上（0001）形成了MG终止的重建，从而形成了MG-FRESTARCATACTANCATANT QUASI-FRICASI-FRESTARCATING QUASI-FRESTARTING QUASI-FRESTANDEREFESTAND-FERESTANDING BILAYERESTING BILAYEREDING BILAYEREDING BILAYEREPRENE（MG-QFSBLG）。在先前对CA交互的外延石墨烯的研究中，尚未考虑缓冲层下方的CA交换。此外，我们没有发现CA或MG在石墨烯层之间插入的证据。但是，我们确实发现CA-QFSBLG和MG-QFSBLG均表现出非常低的3.68和3.78 eV的工作函数，表明N型高掺杂。暴露于环境条件后，我们发现CA-QFSBLG迅速降解，而MG-QFSBLG仍然非常稳定。
The intercalation of epitaxial graphene on SiC(0001) with Ca has been studied extensively, yet precisely where the Ca resides remains elusive. Furthermore, the intercalation of Mg underneath epitaxial graphene on SiC(0001) has not been reported. Here, we use low energy electron diffraction, x-ray photoelectron spectroscopy, secondary electron cut-off photoemission and scanning tunneling microscopy to elucidate the physical and electronic structure of both Ca- and Mg-intercalated epitaxial graphene on 6H-SiC(0001). We find that Ca intercalates underneath the buffer layer and bonds to the Si-terminated SiC surface, breaking the C-Si bonds of the buffer layer i.e. 'freestanding' the buffer layer to form Ca-intercalated quasi-freestanding bilayer graphene (Ca-QFSBLG). The situation is similar for the Mg-intercalation of epitaxial graphene on SiC(0001), where an ordered Mg-terminated reconstruction at the SiC surface and Mg bonds to the Si-terminated SiC surface are formed, resulting in Mg-intercalated quasi-freestanding bilayer graphene (Mg-QFSBLG). Ca-intercalation underneath the buffer layer has not been considered in previous studies of Ca-intercalated epitaxial graphene. Furthermore, we find no evidence that either Ca or Mg intercalates between graphene layers. However, we do find that both Ca-QFSBLG and Mg-QFSBLG exhibit very low workfunctions of 3.68 and 3.78 eV, respectively, indicating high n-type doping. Upon exposure to ambient conditions, we find Ca-QFSBLG degrades rapidly, whereas Mg-QFSBLG remains remarkably stable.
