Twist Angle mapping in layered WS2 by Polarization-Resolved Second Harmonic Generation

• Main Authors: Psilodimitrakopoulos, Sotiris, Mouchliadis, Leonidas, Paradisanos, Ioannis, Kourmoulakis, George, Lemonis, Andreas, Kioseoglou, George, Stratakis, Emmanuel
• Format: Journal Article
• Language: English
• Published: 06-03-2019
• Subjects: Physics - Mesoscale and Nanoscale Physics
• DOI: 10.48550/arxiv.1903.02431

Stacked atomically thin transition metal dichalcogenides (TMDs) exhibit
fundamentally new physical properties compared to those of the individual
layers. The twist angle between the layers plays a crucial role in tuning these
properties. Having a tool that provides highresolution, large area mapping of
the twist angle, would be of great importance in the characterization of such
2D structures. Here we use polarization-resolved second harmonic generation
(P-SHG) imaging microscopy to rapidly map the twist angle in large areas of
overlapping WS2 stacked layers. The robustness of our methodology lies in the
combination of both intensity and polarization measurements of SHG in the
overlapping region. This allows the accurate measurement and consequent
pixel-by-pixel mapping of the twist angle in this area. For the specific case
of 30o twist angle, P-SHG enables imaging of individual layers.