Revealing exciton masses and dielectric properties of monolayer semiconductors with high magnetic fields
Revealing exciton masses and dielectric properties of monolayer semiconductors with high magnetic fields
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DOI：
10.1038/s41467-019-12180-y
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发表时间：
2019-09-13
影响因子：
16.6
通讯作者：
Crooker, S. A.
中科院分区：
文献类型：
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作者：
Goryca, M.;Li, J.;Crooker, S. A.
在半导体物理学中，许多重要的光电材料参数可以在足够大的磁场中通过光谱学实验揭示。对于单层过渡金属二硫族化物半导体，由于载流子质量大和激子结合能大，这种场的尺度基本上是几十特斯拉或更大。在这里，我们报告的吸收光谱单层MoS2，MoSe2，MoTe2，和WS2在非常高的磁场到91 T。我们不仅跟踪激子的基态，而且跟踪其激发态2s，3s，…，ns Rydberg说。这提供了一个直接的实验测量的有效（减少）激子质量和介电性能。激子结合能，激子半径，和自由粒子的带隙也被确定。测得的激子质量比理论预测的要重，特别是对于钼基单层膜。这些结果为合理设计含二维半导体的光电货车德瓦耳斯异质结构提供了必要的定量参数。
In semiconductor physics, many essential optoelectronic material parameters can be experimentally revealed via optical spectroscopy in sufficiently large magnetic fields. For monolayer transition-metal dichalcogenide semiconductors, this field scale is substantialtens of teslas or more-due to heavy carrier masses and huge exciton binding energies. Here we report absorption spectroscopy of monolayer MoS2, MoSe2, MoTe2, and WS2 in very high magnetic fields to 91 T. We follow the diamagnetic shifts and valley Zeeman splittings of not only the exciton's is ground state but also its excited 2s, 3s, ..., ns Rydberg states. This provides a direct experimental measure of the effective (reduced) exciton masses and dielectric properties. Exciton binding energies, exciton radii, and free-particle bandgaps are also determined. The measured exciton masses are heavier than theoretically predicted, especially for Mo-based monolayers. These results provide essential and quantitative parameters for the rational design of opto-electronic van der Waals heterostructures incorporating 2D semiconductors.