SiC衬底上的本征n型外延石墨烯限制了其在微电子器件中的应用,因此,调制和实现p型和电荷中性石墨烯至关重要。金属插层的主要类别,如Ge和Sn,根据第一原理计算结果,被发现是实现这一目标的优秀候选人。它们可以通过插层覆盖来调节石墨烯的导电类型,并为整个插层结构带来有趣的磁性,而不会对石墨烯产生磁性。优于过渡金属插层,如Fe和Mn。发现Ge插层导致石墨烯的双极性掺杂,只有在Ge层和石墨烯之间形成Ge原子时才能获得p型石墨烯。由于石墨烯和变形的Sn插层之间的距离显著增加,因此可以在高Sn插层覆盖率(7/8双层)下实现电荷中性石墨烯。这些发现将为在SiC衬底上开发新的基于石墨烯的自旋电子器件开辟一条途径。
The intrinsic n-type of epitaxial graphene on SiC substrate limits its applications in microelectronic devices, and it is thus vital to modulate and achieve p-type and charge-neutral graphene. The main groups of metal intercalations, such as Ge and Sn, are found to be excellent candidates to achieve this goal based on the first-principle calculation results. They can modulate the conduction type of graphene via
intercalation coverages and bring out interesting magnetic properties to the entire
intercalation structures without inducing magnetism to graphene, which is superior to the transition metal intercalations, such as Fe and Mn. It is found that the Ge
intercalation leads to ambipolar doping of graphene, and the p-type graphene can only be obtained when forming the Ge adatom between Ge layer and graphene. Charge-neutral graphene can be achieved under high Sn
intercalation coverage (7/8 bilayer) owing to the significantly increased distance between graphene and deformed Sn
intercalation. These findings would open up an avenue for developing novel graphene-based spintronic and electric devices on SiC substrate.