Revealing the nanogeometry of WS2 nanoflowers by polarization-resolved Raman spectroscopy

Abstract

Recent studies of Transition Metal Dichalcogenides (TMDs) have revealed exciting optical properties like stable excitons and chiral light-matter interactions. Chemical vapor deposition (CVD) techniques provide a platform for the fabrication of nanostructures with diverse geometries, ranging from horizontal flakes to flower-like structures. Raman spectroscopy is commonly used to characterize TMDs and their properties. Here, we use polarization-resolved Raman spectroscopy to probe the nanogeometry and orientation of WS2 nanoflower petals. Exciting the nanoflowers with linearly polarized light, we observe an enhanced Raman response from flower petals oriented along the excitation polarization direction. Furthermore, the helicity-resolved Raman response of vertically oriented wall-like flower petals exhibits clear differences with horizontally oriented flakes. Although the photoluminescence from the nanoflowers is strongly reduced, the Raman response upon excitation in resonance with the WS2 excitonic transition does reveal the presence of the exciton, which results in a distinct temperature dependence of the Raman response.

arXiv comment19 pages, 4 figures in main text, 8 figures in the supplementary materials

References in corpus (9)

• Atomically thin MoS2: A new direct-gap semiconductor
• Anomalous Lattice Vibrations of Single and Few-Layer MoS2
• MoS_2 as an ideal material for valleytronics: valley-selective circular dichroism and valley Hall effect
• Exciton Binding Energy and Nonhydrogenic Rydberg Series in Monolayer WS2
• Lattice dynamics in mono- and few-layer sheets of WS2 and WSe2
• Helicity resolved Raman scattering of MoS2, MoSe2, WS2 and WSe2 atomic layers
• Anomalously Robust Valley Polarization and Valley Coherence in Bilayer WS2
• Raman scattering excitation spectroscopy in monolayer WS${}_2$
• Morphology-induced spectral modification of self-assembled WS2 pyramids