• DOI:10.1103/PHYSREVLETT.123.027402
• Corpus ID: 199123603

Scanning Tunneling Microscope-Induced Excitonic Luminescence of a Two-Dimensional Semiconductor.

@article{Pommier2019ScanningTM,
  title={Scanning Tunneling Microscope-Induced Excitonic Luminescence of a Two-Dimensional Semiconductor.},
  author={Delphine Pommier and R{\'e}mi Bretel and Luis E. Parra L{\'o}pez and F. Fabre and Andrew J. Mayne and Elizabeth Boer-Duchemin and G'erald Dujardin and Guillaume Schull and St{\'e}phane Berciaud and Eric Le Moal},
  journal={Physical review letters},
  year={2019},
  volume={123 2},
  pages={
          027402
        }
}

• D. Pommier, Rémi Bretel, +7 authors E. Le Moal
• Published 10 July 2019
• Physics
• Physical review letters

The long sought-after goal of locally and spectroscopically probing the excitons of two-dimensional (2D) semiconductors is attained using a scanning tunneling microscope (STM). Excitonic luminescence from monolayer molybdenum diselenide (MoSe_{2}) on a transparent conducting substrate is electrically excited in the tunnel junction of an STM under ambient conditions. By comparing the results with photoluminescence measurements, the emission mechanism is identified as the radiative recombination of bright A excitons. STM-induced luminescence is observed at bias voltages as low as those that correspond to the energy of the optical band gap of MoSe_{2}. The proposed excitation mechanism is resonance energy transfer from the tunneling current to the excitons in the semiconductor, i.e., through virtual photon coupling. Additional mechanisms (e.g., charge injection) may come into play at bias voltages that are higher than the electronic band gap. Photon emission quantum efficiencies of up to 10^{-7} photons per electron are obtained, despite the lack of any participating plasmons. Our results demonstrate a new technique for investigating the excitonic and optoelectronic properties of 2D semiconductors and their heterostructures at the nanometer scale.