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Dielectric Nanoantennas for Strain Engineering in Atomically Thin Two-Dimensional Semiconductors
ACS Photonics ( IF 6.5 ) Pub Date : 2020-08-06 , DOI: 10.1021/acsphotonics.0c00294
Luca Sortino 1 , Matthew Brooks 2 , Panaiot G. Zotev 1 , Armando Genco 1 , Javier Cambiasso 3 , Sandro Mignuzzi 3 , Stefan A. Maier 3, 4 , Guido Burkard 2 , Riccardo Sapienza 3 , Alexander I. Tartakovskii 1
Affiliation  

Atomically thin two-dimensional semiconducting transition metal dichalcogenides (TMDs) can withstand large levels of strain before their irreversible damage occurs. This unique property offers a promising route for control of the optical and electronic properties of TMDs, for instance, by depositing them on nanostructured surfaces, where position-dependent strain can be produced on the nanoscale. Here, we demonstrate strain-induced modifications of the optical properties of mono- and bilayer TMD WSe2 placed on photonic nanoantennas made from gallium phosphide (GaP). Photoluminescence (PL) from the strained areas of the TMD layer is enhanced owing to the efficient coupling with the confined optical mode of the nanoantenna. Thus, by following the shift of the PL peak, we deduce the changes in the strain in WSe2 deposited on the nanoantennas of different radii. In agreement with the presented theory, strain up to ≈1.4% is observed for WSe2 monolayers. We also estimate that >3% strain is achieved in bilayers, accompanied by the emergence of a direct bandgap in this normally indirect-bandgap semiconductor. At cryogenic temperatures, we find evidence of the exciton confinement in the most strained nanoscale parts of the WSe2 layers, as also predicted by our theoretical model. Our results of direct relevance for both dielectric and plasmonic nanoantennas, show that strain in atomically thin semiconductors can be used as an additional parameter for engineering light–matter interaction in nanophotonic devices.

中文翻译:

原子薄二维半导体中用于应变工程的介电纳米天线

原子薄的二维半导体过渡金属二硫化氢(TMDs)在不可逆转的损坏发生之前可以承受较大的应变。这种独特的性质为控制TMD的光学和电子性质提供了一种有希望的途径,例如,通过将它们沉积在纳米结构的表面上,在纳米结构的表面上可以产生位置依赖性的应变。在这里,我们演示了应变诱导的单层和双层TMD WSe 2的光学特性的修饰,该单分子和双层TMD WSe 2放置在由磷化镓(GaP)制成的光子纳米天线上。由于与纳米天线的受限光学模式的有效耦合,来自TMD层应变区域的光致发光(PL)得到增强。因此,通过跟随PL峰的移动,我们可以得出WSe中应变的变化2沉积在不同半径的纳米天线上。与提出的理论一致,对于WSe 2单层观察到的应变高达≈1.4%。我们还估计在双层中实现了> 3%的应变,在这种通常的间接带隙半导体中伴随着直接带隙的出现。在低温下,我们发现了WSe 2层中应变最大的纳米级部分中激子的约束,正如我们的理论模型所预测的那样。我们对电介质和等离子纳米天线都具有直接相关性的结果表明,原子薄半导体中的应变可以用作纳米光子器件中工程光-物质相互作用的附加参数。
更新日期:2020-09-16
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