Dresden 2026 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 51: 2D Materials: Stacking and heterostructures (joint session O/HL/TT)
HL 51.5: Talk
Friday, March 13, 2026, 10:30–10:45, HSZ/0401
Second-Order Nonlinear Imaging for Probing 2D van der Waals Structures — •Tao Yang1, Ben John1, Kyoung P. Lee2, Nasim Mirzajani1, Martin Wolf1, Xiaoqin Li2, Martin Thaemer1, Alexandar Paarmann1, Niclas S. Mueller3, and Alexander P. Fellows1 — 1Fritz Haber Institute, Berlin, Germany — 2University of Texas at Austin, Austin, USA — 3Freie Universitaet Berlin, Berlin, Germany
Twisted and stacked multi-layer architectures offer new opportunities for tailoring the electronic and optical properties of two-dimensional (2D) van der Waals materials. Reliable determination of crystal structure, stacking sequence, and twist angle is therefore crucial. Second-order nonlinear optical microscopy, including second-harmonic and sum-frequency generation (SHG and SFG, respectively), provides high sensitivity to crystal symmetry and orientation in non-centrosymmetric lattices. Recently, we employed heterodyne-detected vibrational SFG microscopy to probe the local structure of hexagonal Boron Nitride (hBN) monolayers with sub-micron resolution. By employing our developed azimuthal-scanning approach, we fully resolved the crystallographic structure and edge termination in monolayer flakes. Here, we extend these measurements to multi-layer hBN structures, using the same azimuthal-scanning approach in a newly developed SHG microscope to gain insight into their different stacking configurations. Our results highlight second-order nonlinear microscopy as a powerful tool for quantitative structural analysis in 2D materials and for future studies of moiré and twisted heterostructures.
Keywords: Nonlinear Imaging; SHG Microscopy; hexagonal Boron Nitride