Ultrafast Band Structure Control of a Two-Dimensional Heterostructure.
Ultrafast Band Structure Control of a Two-Dimensional Heterostructure.
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DOI：
10.1021/acsnano.6b02622
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发表时间：
2016-06
期刊：
影响因子：
17.1
通讯作者：
S. Ulstrup;A. G. Čabo;J. Miwa;J. M. Riley;Signe S. Grønborg;J. Johannsen;C. Cacho;O. Alexander;R. Chapman;E. Springate;M. Bianchi;M. Dendzik;J. Lauritsen;P. King;P. Hofmann
中科院分区：
文献类型：
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作者：
S. Ulstrup;A. G. Čabo;J. Miwa;J. M. Riley;Signe S. Grønborg;J. Johannsen;C. Cacho;O. Alexander;R. Chapman;E. Springate;M. Bianchi;M. Dendzik;J. Lauritsen;P. King;P. Hofmann
二维（2D）半导体的电子结构可以通过屏蔽效应显著改变，无论是来自材料中的自由电荷载流子还是来自周围介质的环境屏蔽。因此，放置在具有其他2D材料的异质结构中的2D半导体的物理性质由内部和层间相互作用的复杂相互作用决定。在这里，使用时间和角度分辨的光电发射，我们能够隔离层分辨的能带结构，更重要的是，瞬态能带结构演变的模型2D异质结构形成的单层MoS2的石墨烯。我们的研究结果揭示了一个明显的重整化的准粒子间隙的二硫化钼层。在光激发之后，带隙在飞秒时间尺度上减小了高达400 meV，这是由于强电子相互作用的持续性，尽管有n掺杂石墨烯的环境屏蔽。这表明嵌入在货车德瓦尔斯键合异质结构中的2D半导体的电子结构和电子动力学具有很大程度的可调谐性。
The electronic structure of two-dimensional (2D) semiconductors can be significantly altered by screening effects, either from free charge carriers in the material or by environmental screening from the surrounding medium. The physical properties of 2D semiconductors placed in a heterostructure with other 2D materials are therefore governed by a complex interplay of both intra- and interlayer interactions. Here, using time- and angle-resolved photoemission, we are able to isolate both the layer-resolved band structure and, more importantly, the transient band structure evolution of a model 2D heterostructure formed of a single layer of MoS2 on graphene. Our results reveal a pronounced renormalization of the quasiparticle gap of the MoS2 layer. Following optical excitation, the band gap is reduced by up to ∼400 meV on femtosecond time scales due to a persistence of strong electronic interactions despite the environmental screening by the n-doped graphene. This points to a large degree of tunability of both the electronic structure and the electron dynamics for 2D semiconductors embedded in a van der Waals-bonded heterostructure.