Calcium intercalation underneath epitaxial graphene on 6H-SiC(0001) were investigated by scanning tunneling microcopy (STM) and density functional theory (DFT) calculations. After the preparation of calcium-adsorbed graphene on 6H-SiC(0001), annealing the sample to 900°C activated the intercalation of the adsorbed calcium into buffer layer (BL), monolayer (1L) and bilayer epitaxial (2L) graphene. Subsequent DFT modeling show the dependence of the most stable intercalation sites for calcium underneath BL, 1L and 2L graphene on the intercalation density. Further DFT calculations indicate charge transfer from the intercalant into graphene layers, leading to the n-type doping of the calcium-intercalated BL, 1L and 2L graphene.

通过扫描隧道显微镜（STM）和密度泛函理论（DFT）计算研究了外延石墨烯在6H-SiC（0001）上的钙嵌入。在6H-SiC（0001）上制备钙吸附的石墨烯后，将样品退火至900°C，激活了将钙吸附插入缓冲层（BL），单层（1L）和双层外延（2L）石墨烯中的过程。随后的DFT建模显示了BL，1L和2L石墨烯下最稳定的钙嵌入位点对嵌入密度的依赖性。进一步的DFT计算表明电荷从嵌入剂转移到石墨烯层中，导致钙嵌入的BL，1L和2L石墨烯的n型掺杂。