Group news

Nano Letters: Quantum-Confined Electronic States observed in the MoS2–WSe2 Moire


2018-02-10

Our work about the MoS2-WSe2 heterobilayers:

Quantum-Confined Electronic States Arising from the Moiré Pattern of MoS2–WSe2 Heterobilayers

has been accepted by Nano Letters:

https://pubs.acs.org/doi/full/10.1021/acs.nanolett.7b05125 (pdf)

 

A two-dimensional (2D) heterobilayer system consisting of MoS2 on WSe2, deposited on epitaxial graphene, is studied by scanning tunneling microscopy and spectroscopy at temperatures of 5 and 80 K. A moiré pattern is observed, arising from lattice mismatch of 3.7% between the MoS2 and WSe2. Significant energy shifts are observed in tunneling spectra observed at the maxima of the moiré corrugation, as compared with spectra obtained at corrugation minima, consistent with prior work. Furthermore, at the minima of the moiré corrugation, sharp peaks in the spectra at energies near the band edges are observed for spectra acquired at 5 K. The peaks correspond to discrete states that are confined within the moiré unit cells. Conductance mapping is employed to reveal the detailed structure of the wave functions of the states. For measurements at 80 K, the sharp peaks in the spectra are absent, and conductance maps of the band edges reveal little structure.

Figure

 

Y.P., S.F, and R.M.F. carried out the STM experiments, and they wrote the paper with inputs from other authors. Y.N. performed the first-principles computations under the supervision of K.C. D.W. performed the NFE modeling. Y.C.L., B.J., and K.Z. synthesized the samples, under the supervision of J.A.R.