Revealing the nanogeometry of WS2 nanoflowersby polarization-resolved Raman spectroscopy
I. Komen (Kavli institute of nanoscience Delft, TU Delft - QN/Kuipers Lab)
S.E. Van Heijst (Kavli institute of nanoscience Delft, TU Delft - QN/Conesa-Boj Lab)
M. Caldarola (TU Delft - QN/Kuipers Lab, Kavli institute of nanoscience Delft)
Sonia Conesa Conesa Boj (TU Delft - QN/Conesa-Boj Lab, Kavli institute of nanoscience Delft)
Kobus Kuipers (TU Delft - QN/Quantum Nanoscience, Kavli institute of nanoscience Delft)
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Abstract
Recent studies of transition metal dichalcogenides (TMDs) have revealed exciting optical properties, such as stable excitons and chiral light–matter interactions. Chemical vapor deposition 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 WS 2 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 WS 2 excitonic transition does reveal the presence of the exciton, which results in a distinct temperature dependence of the Raman response.