Albagami Abdullah, Ambardar Sharad, Hrim Hana, Sahoo Prasana K, Emirov Yusuf, Gutiérrez Humberto R, Voronine Dmitri V
Department of Physics, University of South Florida, Tampa, Florida 33620, United States.
Department of Physics, King Saud University, Riyadh 11362, Kingdom of Saudi Arabia.
ACS Appl Mater Interfaces. 2022 Mar 2;14(8):11006-11015. doi: 10.1021/acsami.1c24486. Epub 2022 Feb 16.
Two-dimensional (2D) semiconducting materials have promising applications in flexible optoelectronics, nanophotonics, and sensing based on the broad tunability of their optical and electronic properties. 2D nanobubbles form exciton funnels due to localized strain that can be used as local emitters for information processing. Their nanoscale optical characterization requires the use of near-field scanning probe microscopy (SPM). However, previous near-field studies of 2D materials were performed on SiO/Si and metallic substrates using the plasmonic gap mode to increase the signal-to-noise ratio. Another challenge is the deterministic control of bubble size and location. We addressed these challenges by investigating the photoluminescence (PL) signals of freestanding monolayer lateral WSe-MoSe heterostructures under the influence of strain exerted by a plasmonic SPM tip. For first time, we performed tip-enhanced PL imaging of freestanding 2D materials and studied the competition between the PL enhancement mechanisms by nanoindentation as a function of the tip-sample distance. We observed the tunability of PL as a function of bubble size, which opens new possibilities to design optoelectronic nanodevices.
二维（2D）半导体材料因其光学和电子特性的广泛可调性，在柔性光电子学、纳米光子学和传感领域有着广阔的应用前景。二维纳米气泡由于局部应变形成激子漏斗，可作为信息处理的局部发射器。它们的纳米级光学表征需要使用近场扫描探针显微镜（SPM）。然而，之前对二维材料的近场研究是在SiO/Si和金属衬底上进行的，利用等离子体间隙模式来提高信噪比。另一个挑战是对气泡尺寸和位置的确定性控制。我们通过研究等离子体SPM尖端施加的应变影响下的独立单层横向WSe-MoSe异质结构的光致发光（PL）信号，解决了这些挑战。我们首次对独立的二维材料进行了尖端增强PL成像，并通过纳米压痕研究了PL增强机制之间的竞争与尖端-样品距离的函数关系。我们观察到PL随气泡尺寸的可调性，这为设计光电子纳米器件开辟了新的可能性。
