标题： 具有局部应变控制的单层WSe2的混合尖端增强纳米光谱和成像 显示英文标题

标题： Hybrid tip-enhanced nano-spectroscopy and -imaging of monolayer WSe2 with local strain control

摘要： 许多二维（2D）材料类别已作为新型电子和光学器件的潜在平台出现。 然而，物理性质受到边缘、晶界和成核位点等纳米尺度异质性的强烈影响。 使用结合探针增强拉曼散射（TERS）和光致发光（TEPL）纳米光谱和成像技术，我们研究了在通过物理气相沉积（PVD）生长的单层WSe2中，与激子特性相关的效应。 具有小于15 nm的空间分辨率，我们解析了PL光谱强度和偏移与晶体边缘和与预期激子扩散长度相关的内部孪晶边界之间的非局部纳米尺度相关性。 通过主动原子力探针相互作用，我们可以在纳米尺度上控制晶体应变，并以可逆（最多24 meV的偏移）和不可逆（最多48 meV的偏移）的方式调节局部带隙。 这使我们能够区分应变的影响与不同结构异质性上缺陷对PL修改的主要影响。 因此，混合纳米光学和纳米机械成像和光谱技术使得系统研究结构和机械自由度与层状二维材料中纳米尺度电子和光学性质之间的耦合成为可能。 显示英文摘要

摘要： Many classes of two-dimensional (2D) materials have emerged as potential platforms for novel electronic and optical devices. However, the physical properties are strongly influenced by nanoscale heterogeneities in the form of edges, grain boundaries, and nucleation sites. Using combined tip-enhanced Raman scattering (TERS) and photoluminescence (TEPL) nano-spectroscopy and -imaging, we study the associated effects on the excitonic properties in monolayer WSe2 grown by physical vapor deposition (PVD). With <15 nm spatial resolution we resolve nonlocal nanoscale correlations of PL spectral intensity and shifts with crystal edges and internal twin boundaries associated with the expected exciton diffusion length. Through an active atomic force tip interaction we can control the crystal strain on the nanoscale, and tune the local bandgap in reversible (up to 24 meV shift) and irreversible (up to 48 meV shift) fashion. This allows us to distinguish the effect of strain from the dominant influence of defects on the PL modification at the different structural heterogeneities. Hybrid nano-optical and nano-mechanical imaging and spectroscopy thus enables the systematic study of the coupling of structural and mechanical degrees of freedom to the nanoscale electronic and optical properties in layered 2D materials.