Moiré Superlattices Formed Between Two-Dimensional Materials and Substrate Lattice

Guan-Hao Chen^1*, Chao-Kai Wen¹, Wei-Chen Chueh¹, Feng-Shen Huang¹, Chun-Liang Lin¹, Juhn-Jong Lin², Wen-Hao Chang¹

¹Electrophysics, National Chiao Tung University, Hsinchu, Taiwan
²Institute of Physics, National Chiao Tung University, Hsinchu, Taiwan

* Presenter:Guan-Hao Chen, email:a0913635136@yahoo.com.tw

Vertically staked heterostructures containing different two-dimensional materials, such as transition metal dichalcogenides (TMDs) and hexagonal boron nitride (h-BN), can create a platform for exploring intriguing physical phenomena. The lattice mismatch and the interlayer twist between the stacked 2D materials can naturally form the Moiré superlattices, which create an additional periodic length scale to modulate the electronic properties. Scanning tunneling microscopy (STM) is an ideal tool to directly probe the Moiré superlattice and the corresponding local electronic structures, such as strains, interlayer spacing and band alignments at atomic scale. In this work, we present STM studies on vertical heterostructures of h-BN/Cu(111) and MoS2/HOPG grown by chemical vapor deposition (CVD). We found that the Moiré superlattices of h-BN/Cu(111) reveal bias dependence, where the Moiré patterns can be observed only when the sample is biased near 4 V and 6 V. We also observed Moiré superlattices in MoS2/HOPG with different periodicities. Scanning tunneling spectroscopy (STS) has also been conducted to unveil the density of states at different sites of the Moiré patterns. Our results show that the band structures can be modulated by the formation of Moiré patterns in the heterostructures.

Keywords: Moiré pattern, Two-Dimensional Materials, Heterostructures, Transition metal dichalcogenides