摘要
Two-dimensional(2D)heterostructures compris-ing of differently stacking atomic layers are attrac-tive owing to its flexible composition as well as the emerging new physicochemical properties.Howev-er,so far many 2D vertical heterojunctions are constructed through transfer methods,inevitably introducing interfacial impurities and thus hindering detailed atomic-level studies.In this work,we have developed a clean two-step fabrication strat-egy by combining ultrahigh vacuum(UHV)molecular beam epitaxy(MBE)growth with am-bient chemical vapor deposition(CVD).We first-ly grew single crystalline graphene film on a SiC substrate under UHV condition,and then synthesized MoS_(2)films on the graphene-SiC sur-face through CVD under inert atmosphere,thus successfully realized the construction of a well-defined MoS_(2)-graphene/SiC heterojunction with clean surface.Particularly,we observed the MoS_(2)can not only grow into monolayer flakes but also form spiral structures,the latter showing layer-by-layer stacks with reduced bandgap down to~1.0 eV.
由不同叠层原子构成的二维异质结构,因其灵活的组合方式和新颖的物理化学性质而备受关注,然而,许多二维垂直异质结都是通过转移方法构建的,这不可避免地会引入界面杂质,阻碍了对其原子尺度的研究.本文通过将超高真空分子束外延生长与化学气相沉积相结合,开发了一种清洁的两步制备策略.首先,利用超高真空分子束外延生长法在SiC基底上生长高质量的双层石墨烯薄膜;然后在情性气氛下通过化学气相沉积法在石墨烯-SiC样品表面合成单层MoS_(2)薄膜,成功实现了具有清洁表面的MoS_(2)-石墨烯/SiC异质结的构建特别值得注意的是,本文观察到MoS_(2)不仅可以生长为单层薄片,还能形成螺旋结构;后者呈现出逐层堆叠的层状结构,并将带隙降低至约1.0 eV.
基金
support from the Natural Science Foundation of Jiangsu Province(No.BK20210124)
the National Natural Science Foun-dation of China(No.12204512,No.22172152,No.21872130,No.22372193)
the National Key Re-search and Development Program of China(No.2021YFA1502801)
the joint funds from the Hefei National Synchrotron Radiation Laboratory(No.KY2060000202)
We also acknowledge financial support from the CAS Project for Young Scientists in Basic Research(No.YSBR-049)
the Fundamental Re-search Funds for the Central Universities(No.WK3510000013,WK2060000066).
