Optical and dielectric properties of MoO3 nanosheets for van der Waals heterostructures
Optical and dielectric properties of MoO3 nanosheets for van der Waals heterostructures
复制标题
DOI：
10.1063/5.0066219
复制
发表时间：
2021-11-29
影响因子：
4
通讯作者：
Gerardot, Brian D.
中科院分区：
文献类型：
--
作者：
Andres-Penares, Daniel;Brotons-Gisbert, Mauro;Gerardot, Brian D.
二维绝缘体是设计和制造货车德瓦耳斯异质结构的关键。它们作为透明电介质间隔物是至关重要的，其厚度可以影响2D器件的光子，电子和光电特性。同时，它们提供异质结构中的有源层的保护。对于这些关键作用，六方氮化硼（hBN）是主要的选择，由于其大的带隙，原子平坦度，低缺陷密度和封装性能。然而，2D绝缘体的广泛目录提供了令人兴奋的机会，可以在某些需要具有额外光学自由度的透明薄层的应用中取代hBN。在这里，我们研究了单晶氧化钼（MoO 3）作为一种替代的2D绝缘体的纳米器件的设计，需要在纳米尺度上的光偏振的精确调整的潜力。首先，我们测量了MoO 3沿着其三个主晶轴的折射率随波长的变化，并确定了其光学性质的面内和面外各向异性。我们发现，MoO 3纳米片的双折射与其他表现出强双折射的2D材料（如黑磷，ReS 2或ReSe 2）相比，特别是在可见光谱范围内，MoO 3具有独特的透明度优势。最后，我们证明了MoO 3介电封装的适用性报告线宽变窄和减少不均匀加宽的二维激子和光学活性量子发射器，分别在一个典型的单层过渡金属二硫族化物半导体。这些结果显示MoO 3作为二维介电层用于操纵垂直二维异质结构中的光偏振的潜力。(c)2021年作者。所有文章内容，除非另有说明，是根据知识共享署名（CC BY）许可证（http：//creativecommons.org/licenses/by/4.0/）。https://doi.org/10.1063/5.0066219
Two-dimensional (2D) insulators are a key element in the design and fabrication of van der Waals heterostructures. They are vital as transparent dielectric spacers whose thickness can influence the photonic, electronic, and optoelectronic properties of 2D devices. Simultaneously, they provide the protection of active layers in the heterostructure. For these critical roles, hexagonal boron nitride (hBN) is the dominant choice due to its large bandgap, atomic flatness, low defect density, and encapsulation properties. However, the broad catalogue of 2D insulators offers exciting opportunities to replace hBN in certain applications that require transparent thin layers with additional optical degrees of freedom. Here, we investigate the potential of single-crystalline molybdenum oxide (MoO3) as an alternative 2D insulator for the design of nanodevices that require precise adjustment of the light polarization at the nanometer scale. First, we measure wavelength-dependent refractive indices of MoO3 along its three main crystal axes and determine the in-plane and out-of-plane anisotropy of its optical properties. We find that the birefringence in MoO3 nanosheets compares favorably with other 2D materials that exhibit strong birefringence, such as black phosphorus, ReS2, or ReSe2, in particular in the visible spectral range, where MoO3 has the unique advantage of transparency. Finally, we demonstrate the suitability of MoO3 for dielectric encapsulation by reporting linewidth narrowing and reduced inhomogeneous broadening of 2D excitons and optically active quantum emitters, respectively, in a prototypical monolayer transition-metal dichalcogenide semiconductor. These results show the potential of MoO3 as a 2D dielectric layer for manipulation of the light polarization in vertical 2D heterostructures.(c) 2021 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http:// creativecommons.org/licenses/by/4.0/). https://doi.org/10.1063/5.0066219