This paper is a contribution to the joint Physical Review Applied and Physical Review Materials collection titled Two-Dimensional Materials and Devices.

Measurements of the homogeneous linewidth of exfoliated ${\mathrm{Mo}\mathrm{Se}}_2$ monolayers reveal significant material improvement with encapsulation, but also higher than expected material inhomogeneity. Multidimensional coherent spectroscopy also directly demonstrates that exfoliated monolayer ${\mathrm{Mo}\mathrm{Se}}_2$ encapsulated in hexagonal boron nitride has an enhanced coherence time and would be useful in high-optical-power applications, where unencapsulated samples would not. We directly measure an excitonic homogeneous linewidth of exfoliated ${\mathrm{Mo}\mathrm{Se}}_2$ that is $0.20\pm 0.02$ meV, corresponding to a dephasing time $T_2\approx 3.3$ ps. Encapsulation reduces the sample inhomogeneity. The inhomogeneous linewidth is roughly 5 times larger than the homogeneous linewidth in even the highest-quality encapsulated materials. Encapsulated ${\mathrm{Mo}\mathrm{Se}}_2$ samples are unaffected by conditions that entirely degrade unencapsulated samples.

• Received 21 December 2018
• Revised 23 April 2020
• Accepted 8 June 2020

DOI:https://doi.org/10.1103/PhysRevApplied.14.021002

This article appears in the following collection:

Two-Dimensional Materials and Devices

Physical Review Applied and Physical Review Materials are pleased to present the Collection on Two-dimensional Materials and Devices, highlighting one of the most interesting fields in Applied Physics and Materials Research. Papers belonging to this collection will be published throughout 2020. The invited articles, and an editorial by the Guest Editor, David Tománek, are linked below.