Regensburg 2025 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
HL: Fachverband Halbleiterphysik
HL 2: 2D Semiconductors and van der Waals Heterostructures I
HL 2.11: Vortrag
Montag, 17. März 2025, 12:15–12:30, H15
Polarized optical contrast spectroscopy of in-plane anisotropic van-der-Waals heterostructures — Ernst Knöckl1,2, •Alexandre Bernard1,2, Alexander Holleitner1,2, and Christoph Kastl1,2 — 1Walter Schottky Institute and Physics Department, TU Munich, Garching, Germany — 2Munich Center for Quantum Science and Technology, München, Germany
To properly exploit interfacial symmetry breakings in van der Waals (vdW) heterostructures, giving rise to emergent behaviors, it is crucial to determine the symmetry axes of the individual layers.
I will discuss polarized optical contrast spectroscopy as a simple and non-destructive approach to characterize the crystalline anisotropy and orientation of 2D materials in vdW heterostructures. We developed a 3D-printed motorized polarization module compatible with typical microscope platforms, allowing broadband polarization-resolved reflectance spectroscopy. We investigated the in-plane birefringence of exfoliated MoO3 thin films (optically transparent) and few-layer WTe2 crystals (semi-metallic). We compared the measured spectra to a model based on a transfer matrix formalism.
Contrasting with other polarization-sensitive approaches, such as Raman or second harmonic generation spectroscopy, this method requires orders of magnitude less excitation power densities, avoiding degradation of delicate layers. Furthermore, it allows quick and simple polarization-sensitive absorbance measurements to resolve anisotropic excitonic properties in symmetry-breaking heterostructures or anisotropic semiconductors.
Keywords: 2D anisotropic crystals; optical characterization; van der Waals heterostructures; MoO3; WTe2