Toplayer-Dependent Crystallographic Orientation Imaging in the Bilayer Two-Dimensional Materials with Transverse Shear Microscopy

TL;DR

This study uses transverse shear microscopy to directly observe how the top layer of bilayer 2D materials influences their crystallographic orientation and puckering behavior, revealing layer-dependent nanomechanical properties.

Contribution

It introduces a novel application of TSM for imaging top-layer-dependent crystallographic orientations in bilayer 2D materials, highlighting the layer-specific puckering effects.

Findings

Puckering mainly occurs on the top layer of 2D materials.

Underlying crystalline substrates have minimal impact on puckering.

TSM effectively images top-layer-dependent crystallographic orientations.

Abstract

Nanocontact properties of two-dimensional (2D) materials are closely dependent on their unique nanomechanical systems, such as the number of atomic layers and the supporting substrate. Here, we report a direct observation of toplayer-dependent crystallographic orientation imaging of 2D materials with the transverse shear microscopy (TSM). Three typical nanomechanical systems, MoS2 on the amorphous SiO2/Si, graphene on the amorphous SiO2/Si, and MoS2 on the crystallized Al2O3, have been investigated in detail. This experimental observation reveals that puckering behaviour mainly occurs on the top layer of 2D materials, which is attributed to its direct contact adhesion with the AFM tip. Furthermore, the result of crystallographic orientation imaging of MoS2/SiO2/Si and MoS2/Al2O3 indicated that the underlying crystalline substrates almost do not contribute to the puckering effect of 2D materials. Our work directly revealed the top layer dependent puckering properties of 2D material, and demonstrate the general applications of TSM in the bilayer 2D systems.