2021/04/12 by Sotiris Psilodimitrakopoulos, Psilodimitrakopoulos, S., Andrey Orekhov +17
Materials Science · #2D Materials and Applications #FOS: Physical sciences #Ga2O3 and related materials #Materials Science (cond-mat.mtrl-sci) #Quantum Dots Synthesis And Properties
paper · pdf · doi:10.48550/arxiv.2104.05783
openalex publication_date 2021/04/12 · openalex created_date 2021/04/26 · openalex updated_date 2026/07/28
Atomically thin two-dimensional (2D) materials can be vertically stacked with van der Waals bonds, which enable interlayer coupling. In the particular case of transition metal dichalcogenide (TMD) bilayers, the relative direction between the two monolayers, coined as twist-angle, modifies the crystal symmetry and creates a superlattice with exciting properties. Here, we demonstrate an all-optical method for pixel-by-pixel mapping of the twist-angle with resolution of 0.23 degrees, via polarization-resolved second harmonic generation (P-SHG) microscopy and we compare it with four-dimensional scanning transmission electron microscopy (4D-STEM). It is found that the twist-angle imaging of WS2 bilayers, using the P-SHG technique is in excellent agreement with that obtained using electron diffraction. The main advantages of the optical approach are that the characterization is performed on the same substrate that the device is created on and that it is three orders of magnitude faster than the 4D-STEM. We envisage that the optical P-SHG imaging could become the gold standard for the quality examination of TMD superlattice-based devices.