硕士生胡比奇同学在国际纳米权威期刊Nano Research上发表论文
课题组硕士生胡比奇同学在国际纳米权威期刊Nano Research上发表论文
近日，课题组硕士生胡比奇同学在刘老师的指导下，以第一作者在国际纳米权威期刊《纳米研究》(Nano Research，影响因子9.5)上发表题为“Unveiling Optical Anisotropy in Disrupted Symmetry WSe2/SiP Heterostructures”(WSe2/SiP异质结中光学各向异性的特性)的实验论文。
图：WSe2/SiP异质结中光学各向异性的特性
二维过渡金属二硫属化合物(TMDs)因其卓越的光学、电学、热学和机械性能而备受科学界关注。它们在光电探测器和纳米电子器件等应用中展现出广阔前景。TMDs的物理性质与其结构特性密切相关，范德瓦尔斯(vdW)材料的低对称性晶格结构赋予其各向异性，使其在热电、谷电子学和激子行为等领域具有重要应用价值。然而，天然各向异性vdW材料的稀缺以及制备高质量、大规模各向异性材料的挑战，凸显了探索新型二维各向异性材料的必要性。因此，构建各向异性异质结构在人工操纵vdW材料的晶格结构以实现高性能光电器件方面起着至关重要的作用。
在本研究中，我们创新的提出了一种通过构建WSe2和SiP片材的异质结构来破坏单层WSe2的C3旋转对称性的策略。通过综合实验研究和第一性原理计算，我们阐明了在WSe2/SiP异质结构中，源自WSe2的激子——包括中性和带电激子——表现出显著的各向异性，并且在温度变化下保持稳定。值得注意的是，我们观察到各向异性比值高达1.5，表明存在显著的各向异性。此外，我们通过施加磁场证明了激子各向异性的可调性，随着磁场强度的增加，各向异性比值显著减少，从1.57降至1.18。令人瞩目的是，随着磁场的增加，异质结各向异性比值的变化达到24.8%。我们的研究发现，WSe2单层的C3旋转对称性的破坏源于层内非均匀的电荷密度分布，表现出镜像对称性。这些结果强调了异质结构工程在调整各向同性材料特性方面的潜力，并为推进各向异性器件在各个领域的应用提供了有前景的途径。
论文链接：https://link.springer.com/article/10.1007/s12274-024-6857-1
Comments:
The paper "Unveiling Optical Anisotropy in Disrupted Symmetry WSe2/SiP Heterostructures" presents a significant advancement in the field of two-dimensional transition metal dichalcogenides (TMDs). By disrupting the C3 rotational symmetry of monolayer WSe2 through the incorporation of SiP flakes, the authors have successfully demonstrated pronounced and tunable optical anisotropy in the WSe2/SiP heterostructure. This work addresses a critical limitation posed by the inherent high symmetry of TMD lattices, thereby enhancing their functional versatility.
The comprehensive experimental investigations and first-principle calculations provide robust evidence that both neutral and charged excitons from WSe2 exhibit substantial anisotropy, resilient to temperature variations. The observed anisotropic ratio, reaching up to 1.5, signifies a considerable degree of anisotropy. Moreover, the tunability of this anisotropy via the application of a magnetic field, resulting in a significant reduction of the anisotropic ratio from 1.57 to 1.18, is particularly noteworthy. The 24.8% change in heterojunction anisotropy ratio with increasing magnetic field strength highlights the dynamic control achievable in these heterostructures.
The elucidation that the perturbation of the C3 rotational symmetry is due to a non-uniform charge density distribution, exhibiting mirror symmetry within the WSe2 monolayer, provides valuable insights into the underlying mechanisms. This finding not only underscores the potential of heterostructure engineering in tailoring the properties of isotropic materials but also opens promising avenues for the development and application of anisotropic devices across various technological fields.
Overall, this paper makes a substantial contribution to the understanding and application of TMD-based heterostructures, offering new strategies for exploiting optical anisotropy in next-generation optoelectronic devices.