posted on 2021-12-08, 18:34authored byNoémie Bonnet, Hae Yeon Lee, Fuhui Shao, Steffi Y. Woo, Jean-Denis Blazit, Kenji Watanabe, Takashi Taniguchi, Alberto Zobelli, Odile Stéphan, Mathieu Kociak, Silvija Gradečak, Luiz H. G. Tizei
Structural,
electronic, and chemical nanoscale modifications of
transition metal dichalcogenide monolayers alter their optical properties.
A key missing element for complete control is a direct spatial correlation
of optical response to nanoscale modifications due to the large gap
in spatial resolution between optical spectroscopy and nanometer-resolved
techniques. Here, we bridge this gap by obtaining nanometer-resolved
optical properties using electron spectroscopy at cryogenic temperatures,
specifically electron energy loss spectroscopy for absorption and
cathodoluminescence for emission, which are then directly correlated
to chemical and structural information. In an h-BN/WS2/h-BN
heterostructure, we observe local modulation of the trion (X–) emission due to tens of nanometer wide dielectric patches. Trion
emission also increases in regions where charge accumulation occurs,
close to the carbon film supporting the heterostructures. The localized
exciton emission (L) detected here is not correlated to strain above
1%, suggesting point defects might be involved in their formation.