2019/04/30 by M. Goryca, J. Li, A. V. Stier +8 · 2 citations
Physics and Astronomy · #cond-mat.mes-hall #cond-mat.mtrl-sci
paper · pdf · doi:10.1038/s41467-019-12180-y
published as Nature Communications 10, 4172 (2019) · updated; now also including data on MoTe2. Accepted & in press, Nature Commun
arxiv created 2019/08/28 · arxiv updated 2020/08/20
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 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 1s 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.