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Molecular Foundry

HIGHLIGHTSHyperspectral imaging of exciton confinement within a moiré unit cell with a subnanometer electron probe
January 21, 2023

Scientific Achievement

(b-c) Comparison of spatially resolved experimental and theory for different stacking configurations. (d) Experimental unit cell averaged and tiled EELS map. (e) Theoretically calculated oscillator strength distribution of the peak I exciton, with similar radial blurring as the experiment.

A team of Molecular Foundry staff and users have, for the first time, created and directly imaged the localization of excitons in a simple stack of two atomically thin materials.

Significance and Impact

The ability to localize excitons on specific lattice sites and the potential to create an exciton lattice by simply stacking 2D materials has a variety of applications, from designer optoelectronic devices to hosting pre-defined defect states for quantum information science.

Research Details

  • The team fabricated devices by stacking tungsten disulfide (WS2) and tungsten diselenide (WSe2)
  • The researchers combined information from hundreds of measurements to determine the probable locations of excitons.
  • Theoretical calculations revealed that large atomic reconstructions take place in the stacked materials, which modulate the electronic structure to form a periodic array of “traps” where excitons become localized.
S. Susarla, M.H. Naik, D.D. Blach, J. Zipfel, T. Taniguchi, K. Watanabe, L. Huang, R. Ramesh, F.H. Da Jornada, S.G. Louie, P. Ercius, A. Raja. Science 378, 6625, 1235-1239. DOI: 10.1126/science.add9294

Read the news article on this paper.

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