Goryca M, Li J, Stier A V, Taniguchi T, Watanabe K, Courtade E, Shree S, Robert C, Urbaszek B, Marie X, Crooker S A
National High Magnetic Field Laboratory, Los Alamos National Lab, Los Alamos, NM, 87545, USA.
National Institute for Materials Science, Tsukuba, Ibaraki, 305-0044, Japan.
Nat Commun. 2019 Sep 13;10(1):4172. doi: 10.1038/s41467-019-12180-y.
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 substantial-tens of teslas or more-due to heavy carrier masses and huge exciton binding energies. Here we report absorption spectroscopy of monolayer [Formula: see text], and [Formula: see text] in very high magnetic fields to 91 T. We follow the diamagnetic shifts and valley Zeeman splittings of not only the exciton's [Formula: see text] ground state but also its excited [Formula: see text] 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.
在半导体物理学中，许多重要的光电子材料参数可以通过在足够强的磁场中进行光谱实验来揭示。对于单层过渡金属二卤化物半导体，由于重的载流子质量和巨大的激子结合能，这个磁场强度范围相当大——几十特斯拉或更高。在此，我们报告了单层[化学式：见原文]、[化学式：见原文]在高达91T的极高磁场中的吸收光谱。我们不仅跟踪了激子的[化学式：见原文]基态的抗磁位移和谷塞曼分裂，还跟踪了其激发的[化学式：见原文]里德堡态的相关情况。这提供了有效（约化）激子质量和介电性质的直接实验测量。还确定了激子结合能、激子半径和自由粒子带隙。测量得到的激子质量比理论预测的更重，特别是对于基于钼的单层材料。这些结果为合理设计包含二维半导体的光电子范德华异质结构提供了重要的定量参数。
