Tip-Induced and Electrical Control of the Photoluminescence Yield of Monolayer WS₂

Abstract

The photoluminescence (PL) of monolayer tungsten disulfide (WS 2 ) is locally and electrically controlled using the nonplasmonic tip and tunneling current of a scanning tunneling microscope (STM). The spatial and spectral distribution of the emitted light is determined using an optical microscope. When the STM tip is engaged, short-range PL quenching due to near-field electromagnetic effects is present, independent of the sign and value of the bias voltage applied to the tip−sample tunneling junction. In addition, a bias-voltage-dependent long-range PL quenching is measured when the sample is positively biased. We explain these observations by considering the native n-doping of monolayer WS 2 and the charge carrier density gradients induced by electron tunneling in micrometer-scale areas around the tip position. The combination of wide-field PL microscopy and charge carrier injection using an STM opens up new ways to explore the interplay between excitons and charge carriers in two-dimensional semiconductors.

Dynamical control of nanoscale light-matter interactions in low-dimensional quantum materials

“…7f. In addition, we envision that the near-field polarization control at the tip can further expand to lightmatter interactions in the ultrafast time domain 174,175 . Notably, fs-pulsed laser excitation at plasmonic tips has been shown to reveal the nanoscale nonlinear optical phenomena in 2D van der Waals materials 176,177 .…”

Impacts of dielectric screening on the luminescence of monolayer WSe2

“…Indeed, the observation of residues trapped in the interface of vdW's materials and surfaces has been widely reported [39][40][41][42][43][44][45][46][47][48][49][50][51]. The general conclusion is that these adsorbates can compromise the efficiency of the assembly, introducing extrinsic disorder [46] and acting as a decoupling media between the layers composing the heterostructure [51,52].…”

“…Indeed, the observation of residues trapped in the interface of vdW's materials and surfaces has been widely reported [39][40][41][42][43][44][45][46][47][48][49][50][51]. The general conclusion is that these adsorbates can compromise the efficiency of the assembly, introducing extrinsic disorder [46] and acting as a decoupling media between the layers composing the heterostructure [51,52]. Several studies [48,[52][53][54] show that thermal annealing can be an effective strategy to remove these contaminants, ensuring a tight interlayer coupling in heterostructures containing TMDC-MLs.…”