Wu Qilong, Fu Xiaoshuai, Yang Ke, Wu Hongyu, Liu Li, Zhang Li, Tian Yuan, Yin Long-Jing, Huang Wei-Qing, Zhang Wen, Wong Ping Kwan Johnny, Zhang Lijie, Wee Andrew T S, Qin Zhihui
Key Laboratory for Micro/Nano Optoelectronic Devices of Ministry of Education & Hunan Provincial Key Laboratory of Low-Dimensional Structural Physics and Devices, School of Physics and Electronics, Hunan University, Changsha 410082, People's Republic of China.
School of Microelectronics & School of Electronics and Information, Northwestern Polytechnical University, Xi'an 710072, People's Republic of China.
ACS Nano. 2021 Mar 23;15(3):4481-4489. doi: 10.1021/acsnano.0c08513. Epub 2021 Mar 3.
As a two-dimensional semiconductor with many physical properties, including, notably, layer-controlled electronic bandgap and coupled spin-valley degree of freedom, monolayer MoSe is a strong candidate material for next-generation opto- and valley-electronic devices. However, due to substrate effects such as lattice mismatch and dielectric screening, preserving the monolayer's intrinsic properties remains challenging. This issue is generally significant for metallic substrates whose active surfaces are commonly utilized to achieve direct chemical or physical vapor growth of the monolayer films. Here, we demonstrate high-temperature-annealed Au foil with well-defined (100) facets as a weakly interacting substrate for atmospheric pressure chemical vapor deposition of highly crystalline monolayer MoSe. Low-temperature scanning tunneling microscopy/spectroscopy measurements reveal a honeycomb structure of MoSe with a quasi-particle bandgap of 1.96 eV, a value comparable with other weakly interacting systems such as MoSe/graphite. Density functional theory calculations indicate that the Au(100) surface exhibits the preferred energetics to electronically decouple from MoSe, compared with the (110) and (111) crystal planes. This weak coupling is critical for the easy transfer of monolayers to another host substrate. Our study demonstrates a practical means to produce high-quality monolayers of transition-metal dichalcogenides, viable for both fundamental and application studies.
作为一种具有多种物理性质的二维半导体，特别是具有层控电子带隙和耦合自旋-谷自由度，单层MoSe是下一代光电器件和谷电子器件的有力候选材料。然而，由于晶格失配和介电屏蔽等衬底效应，保持单层的固有性质仍然具有挑战性。对于金属衬底来说，这个问题通常很重要，因为其活性表面通常用于实现单层膜的直接化学或物理气相生长。在这里，我们展示了具有明确（100）面的高温退火金箔，作为用于大气压化学气相沉积高度结晶单层MoSe的弱相互作用衬底。低温扫描隧道显微镜/光谱测量揭示了MoSe的蜂窝结构，其准粒子带隙为1.96 eV，该值与其他弱相互作用系统如MoSe/石墨相当。密度泛函理论计算表明，与（110）和（111）晶面相比，Au（100）表面表现出与MoSe电子解耦的优选能量学。这种弱耦合对于单层容易转移到另一个主体衬底至关重要。我们的研究展示了一种制备高质量过渡金属二硫属化物单层的实用方法，对基础研究和应用研究都可行。
