Abstract
Chemical doping is an effective method for tailoring physical properties of semiconductors. It has been long known that trace-level doping can obviously influence vibrational properties of bulk semiconductors. Nevertheless, less is known about the effect of chemical doping on the lattice dynamics of two-dimensional (2D) semiconductors although electron-phonon interaction can significantly influence the electronic mobility of the 2D semiconductors. In this study, we carried out Raman-scattering measurements in combine with atom-resolved scanning transmission electron microscope characterization to unveil the effects of Re doping on the phonon dispersion of single-layer (1L) $\mathrm{Mo}{\mathrm{S}}_{2}$. Second-order Raman modes in a wide spectral range reveal the distinct softening of the longitudinal acoustic phonon branch of 1L $\mathrm{Mo}{\mathrm{S}}_{2}$ but with an imperceptible shift of other branches. Such zone-edge phonon renormalization mainly results from electron doping via strong electron-phonon coupling along with a minor contribution from the increased atomic weight from heavier Re dopants. This study enriches the understanding of dopant-host interactions in 2D materials in the aspect of phonons, which is important for tailoring physical properties of 2D materials, such as thermal and electrical transport.
Published Version
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