Local probe of the interlayer coupling strength of few-layers SnSe by contact-resonance atomic force microscopy

TL;DR

This study employs contact-resonance atomic force microscopy to directly measure and analyze the interlayer bonding strength in few-layer SnSe, providing insights into its physical and chemical properties.

Contribution

It introduces a nondestructive CR AFM methodology for direct interlayer bonding characterization in 2D materials, combining experimental and theoretical analysis.

Findings

Interlayer bonding strength quantified in SnSe.

Comparison with SiO2 substrate highlights bonding differences.

Methodology applicable to other 2D layered materials.

Abstract

The interlayer bonding in two dimensional materials is particularly important because it is not only related to their physical and chemical stability but also affects their mechanical, thermal, electronic, optical, and other properties. To address this issue, we report the direct characterization of the interlayer bonding in 2D SnSe using contact-resonance atomic force microscopy in this study. Site specific CR spectroscopy and CR force spectroscopy measurements are performed on both SnSe and its supporting SiO2 substrate comparatively. Based on the cantilever and contact mechanic models, the contact stiffness and vertical Young's modulus are evaluated in comparison with SiO2 as a reference material. The interlayer bonding of SnSe is further analyzed in combination with the semi-analytical model and density functional theory calculations. The direct characterization of interlayer interactions using this nondestructive methodology of CR AFM would facilitate a better understanding of the physical and chemical properties of 2D layered materials, specifically for interlayer intercalation and vertical heterostructures.