Liu Baishan, Liao Qingliang, Zhang Xiankun, Du Junli, Ou Yang, Xiao Jiankun, Kang Zhuo, Zhang Zheng, Zhang Yue
Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies , University of Science and Technology Beijing , Beijing 100083 , People's Republic of China.
State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering , University of Science and Technology Beijing , Beijing 100083 , People's Republic of China.
ACS Nano. 2019 Aug 27;13(8):9057-9066. doi: 10.1021/acsnano.9b03239. Epub 2019 Jul 23.
van der Waals (vdWs) heterostructures have provided a platform for nanoscale material integrations and enabled promise for use in optoelectronic devices. Because of the ultrastrength of two-dimensional materials, strain engineering is considered as an effective way to tune their band structures and further tailor the interface performance of vdWs heterostructures. However, the less-constrained vdWs interfaces make the traditional strain technique via lattice-mismatched growth infeasible. Here, we report a strategy to construct mixed-dimensional heterostructure arrays with periodically strain-engineered vdWs interfaces utilizing one-dimensional semiconductor-induced nanoindentation. Using monolayer MoS (1L-MoS)/ZnO heterostructure arrays as a model system, we demonstrate inhomogeneous built-in strain gradient at the heterointerfaces ranging from 0 to 0.6% tensile. Through systematic optical characterization of the hybrid structures, we verify that strain can improve the interfacial charge transfer efficiency. Consequently, we observe that the photoluminescence (PL) emission of 1L-MoS at strained interfaces is dramatically quenched more than 50% with respect to that at unstrained interfaces. Furthermore, we confirm that the strain-optimized interfacial carrier behavior is attributed to the reduction of interfacial barrier height, which originated from the strain-dependent Fermi level of 1L-MoS. These results demonstrate that strain provides another degree of freedom in tuning the vdWs interface performance and our method developed here should enable flexibility in achieving more sophisticated vdWs integration via strain engineering.
范德华（vdWs）异质结构为纳米级材料集成提供了一个平台，并有望应用于光电器件。由于二维材料具有超强的特性，应变工程被认为是调节其能带结构以及进一步优化vdWs异质结构界面性能的有效方法。然而，vdWs界面的约束较少，使得通过晶格失配生长的传统应变技术变得不可行。在此，我们报告了一种策略，即利用一维半导体诱导的纳米压痕来构建具有周期性应变工程vdWs界面的混合维异质结构阵列。以单层MoS（1L-MoS）/ZnO异质结构阵列为模型系统，我们展示了异质界面处不均匀的内置应变梯度，范围从0到0.6%的拉伸应变。通过对混合结构进行系统的光学表征，我们验证了应变可以提高界面电荷转移效率。因此，我们观察到，与未应变界面相比，应变界面处1L-MoS的光致发光（PL）发射显著猝灭了50%以上。此外，我们证实，应变优化的界面载流子行为归因于界面势垒高度的降低，这源于1L-MoS的应变依赖费米能级。这些结果表明，应变在调节vdWs界面性能方面提供了另一个自由度，并且我们在此开发的方法应该能够通过应变工程灵活地实现更复杂的vdWs集成。
