Trainer Daniel J, Zhang Yuan, Bobba Fabrizio, Xi Xiaoxing, Hla Saw-Wai, Iavarone Maria
Physics Department , Temple University , Philadelphia , Pennsylvania 19122 , United States.
Center for Nanoscale Materials , Argonne National Laboratory , Lemont , Illinois 60439 , United States.
ACS Nano. 2019 Jul 23;13(7):8284-8291. doi: 10.1021/acsnano.9b03652. Epub 2019 Jul 8.
The ability to control nanoscale electronic properties by introducing macroscopic strain is of critical importance for the implementation of two-dimensional (2D) materials into flexible electronics and next-generation strain engineering devices. In this work, we correlate the atomic-scale lattice deformation with a systematic macroscopic bending of monolayer molybdenum disulfide films by using scanning tunneling microscopy and spectroscopy implemented with a custom-built sample holder to control the strain. Using this technique, we are able to induce strains of up to 3% before slipping effects take place and relaxation mechanisms prevail. We find a reduction of the quasiparticle bandgap of about 400 meV per percent local strain measured with a minimum gap of 1.2 eV. Furthermore, unintentional nanoscale strain relaxation of van der Waals monolayer sheets can negatively impact strain engineered device performance. Here we investigate such strain relaxation mechanisms that include one-dimensional ripples and 2D wrinkles which alter the spatial electronic density of states and strain distribution on the atomic scale.
通过引入宏观应变来控制纳米级电子特性的能力对于将二维（2D）材料应用于柔性电子器件和下一代应变工程器件至关重要。在这项工作中，我们通过使用扫描隧道显微镜和光谱技术，结合定制的样品架来控制应变，将单层二硫化钼薄膜的原子尺度晶格变形与系统的宏观弯曲相关联。使用这种技术，我们能够在滑移效应发生和弛豫机制占主导之前诱导高达3%的应变。我们发现，每百分之一的局部应变会使准粒子带隙减小约400 meV，最小带隙为1.2 eV。此外，范德华单层片材的无意纳米级应变弛豫会对应变工程器件的性能产生负面影响。在这里，我们研究了这种应变弛豫机制，包括一维波纹和二维皱纹，它们会在原子尺度上改变空间电子态密度和应变分布。
