AVS 65th International Symposium & Exhibition
    2D Materials Focus Topic Thursday Sessions
       Session 2D+EM+MN+NS-ThA

Paper 2D+EM+MN+NS-ThA1
Double Indirect Interlayer Exciton in a MoSe2/WSe2 van der Waals Heterostructure

Thursday, October 25, 2018, 2:20 pm, Room 201B

Session: Novel Quantum Phenomena in 2D Materials
Presenter: Aubrey Hanbicki, Naval Research Laboratory
Authors: A.T. Hanbicki, Naval Research Laboratory
H.-J. Chuang, Naval Research Laboratory
M. Rosenberger, Naval Research Laboratory
C.S. Hellberg, Naval Research Laboratory
S.V. Sivaram, Naval Research Laboratory
K.M. McCreary, Naval Research Laboratory
I. Mazin, Naval Research Laboratory
B.T. Jonker, Naval Research Laboratory
Correspondent: Click to Email
Tailoring semiconductor heterostructures for specific functionalities has led to varied opto-electronic devices including solar cells, photodetectors, light-emitting diodes and lasers. An emerging class of heterostructures involves monolayer semiconductors such as many of the transition metal dichalcogenides (TMDs) which can be combined to form van der Waals heterostructures (vdWHs). vdWHs offer novel functionalities making them promising hosts for future devices. One unique new heterostructure property is an interlayer exciton (ILE), a spatially indirect, bound electron-hole pair with the electron in one TMD layer and the hole in the other. Here, using state-of-the-art preparation techniques, we are able to resolve emission from the ILE in a MoSe2/WSe2 heterostructure into two distinct peaks separated by 24 meV at zero field. These peaks have nearly equal intensity, indicating they are of common character, and have opposite circular polarizations when excited with circularly polarized light. Ab initio calculations successfully account for these observations – they show that both emission features originate from excitonic transitions that are indirect in momentum space and are split by spin-orbit coupling. Also, the electron is strongly hybridized between both the MoSe2 and WSe2 layers, with significant weight in both layers, contrary to the commonly assumed model. Thus, the transitions are not purely interlayer in character. This work represents a significant advance in our understanding of the static and dynamic properties of TMD heterostructures.

This research was performed while H.-J.C. held an American Society for Engineering Education fellowship and M.R.R and S.V.S held a National Research Council fellowship at NRL. This work was supported by core programs at NRL and the NRL Nanoscience Institute. This work was also supported in part by a grant of computer time from the DoD High Performance Computing Modernization Program at the U.S. Army Research Laboratory Supercomputing Resource Center.