Ultralocalized Optoelectronic Properties of Nanobubbles in 2D Semiconductors
Ultralocalized Optoelectronic Properties of Nanobubbles in 2D Semiconductors
复制标题
DOI：
10.1021/acs.nanolett.2c02265
复制
发表时间：
2022-09-19
期刊：
影响因子：
10.8
通讯作者：
Pasupathy, Abhay N.
中科院分区：
文献类型：
--
作者：
Shabani, Sara;Darlington, Thomas P.;Pasupathy, Abhay N.
过渡金属二硫属化物的光学性质先前已通过使用机械和电纳米结构在纳米尺度上进行了修改。然而，迄今为止，还缺乏将局域电子结构与此类结构的发射特性联系起来的清晰实验图。在这里，我们结合使用扫描隧道显微镜（STM）和近场光致发光（nano-PL）来探测MoSe2上WSe2双层异质结构中单个纳米气泡的电子和光学特性。我们从隧道光谱中发现，电子态深深地集中在这些气泡边缘的间隙中，这与层中化学缺陷的存在无关。我们还展示了气泡上局部带隙的显着变化，在类似于 20 nm 的长度范围内不断演化到气泡边缘。 Nano-PL 测量观察到进入气泡时层间激子的连续红移，与 STM 测量的带间跃迁一致。我们使用自洽薛定谔-泊松模拟来捕捉实验结果的本质，并发现气泡区域的强掺杂是实现观察到的局域态以及机械应变的关键因素。
The optical properties of transition-metal dichalcogenides have previously been modified at the nanoscale by using mechanical and electrical nanostructuring. However, a clear experimental picture relating the local electronic structure with emission properties in such structures has so far been lacking. Here, we use a combination of scanning tunneling microscopy (STM) and near-field photoluminescence (nano-PL) to probe the electronic and optical properties of single nanobubbles in bilayer heterostructures of WSe2 on MoSe2. We show from tunneling spectroscopy that there are electronic states deeply localized in the gap at the edge of such bubbles, which are independent of the presence of chemical defects in the layers. We also show a significant change in the local band gap on the bubble, with a continuous evolution to the edge of the bubble over a length scale of similar to 20 nm. Nano-PL measurements observe a continuous redshift of the interlayer exciton on entering the bubble, in agreement with the band-to-band transitions measured by STM. We use self-consistent Schrodinger-Poisson simulations to capture the essence of the experimental results and find that strong doping in the bubble region is a key ingredient to achieving the observed localized states, together with mechanical strain.