Valley-polarized exciton dynamics in a 2D semiconductor heterostructure
Valley-polarized exciton dynamics in a 2D semiconductor heterostructure
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DOI：
10.1126/science.aac7820
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发表时间：
2016-02-12
期刊：
影响因子：
56.9
通讯作者：
Xu, Xiaodong
中科院分区：
文献类型：
--
作者：
Rivera, Pasqual;Seyler, Kyle L.;Xu, Xiaodong
包括不同单层半导体的异质结构为基础科学和器件技术提供了有吸引力的环境，例如在谷电子学的新兴领域中。我们在单层WSe 2-MoSe 2垂直异质结中实现了谷特异性层间激子。我们利用圆偏振光泵浦产生了层间激子自旋谷极化，并确定了40纳秒的谷寿命。这种长寿命的极化使得谷极化激子云的膨胀超过几微米的可视化成为可能。极化的空间图案随着激子密度的增加而演变成环，这是谷激子交换相互作用的表现。我们的工作介绍了货车德瓦耳斯异质结构作为一个有前途的平台，从其中研究谷激子物理。
Heterostructures comprising different monolayer semiconductors provide an attractive setting for fundamental science and device technologies, such as in the emerging field of valleytronics. We realized valley-specific interlayer excitons in monolayer WSe2-MoSe2 vertical heterostructures. We created interlayer exciton spin-valley polarization by means of circularly polarized optical pumping and determined a valley lifetime of 40 nanoseconds. This long-lived polarization enables the visualization of the expansion of a valley-polarized exciton cloud over several micrometers. The spatial pattern of the polarization evolves into a ring with increasing exciton density, a manifestation of valley exciton exchange interactions. Our work introduces van der Waals heterostructures as a promising platform from which to study valley exciton physics.