Li Zidong, Lu Xiaobo, Cordovilla Leon Darwin F, Lyu Zhengyang, Xie Hongchao, Hou Jize, Lu Yanzhao, Guo Xiaoyu, Kaczmarek Austin, Taniguchi Takashi, Watanabe Kenji, Zhao Liuyan, Yang Li, Deotare Parag B
International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Ibaraki 305-0044, Japan.
Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan.
ACS Nano. 2021 Jan 26;15(1):1539-1547. doi: 10.1021/acsnano.0c08981. Epub 2021 Jan 8.
A moiré superlattice formed by stacking two lattice mismatched transition metal dichalcogenide monolayers, functions as a diffusion barrier that affects the energy transport and dynamics of interlayer excitons (electron and hole spatially concentrated in different monolayers). In this work, we experimentally quantify the diffusion barrier experienced by interlayer excitons in hexagonal boron nitride-encapsulated molybdenum diselenide/tungsten diselenide (MoSe/WSe) heterostructures with different twist angles. We observe the localization of interlayer excitons at low temperature and the temperature-activated diffusivity as a function of twist angle and hence attribute it to the deep periodic potentials arising from the moiré superlattice. We further support the observations with theoretical calculations, Monte Carlo simulations, and a three-level model that represents the exciton dynamics at various temperatures.
通过堆叠两个晶格失配的过渡金属二硫属化物单层形成的莫尔超晶格，起到扩散势垒的作用，影响层间激子（电子和空穴在空间上集中在不同单层中）的能量传输和动力学。在这项工作中，我们通过实验量化了六方氮化硼封装的具有不同扭转角的二硒化钼/二硒化钨（MoSe₂/WSe₂）异质结构中层间激子所经历的扩散势垒。我们观察到低温下层间激子的局域化以及作为扭转角函数的温度激活扩散率，并因此将其归因于莫尔超晶格产生的深周期势。我们通过理论计算、蒙特卡罗模拟以及一个表示不同温度下激子动力学的三能级模型进一步支持了这些观察结果。
