Dynamics of an interfacial bubble controls adhesion mechanics in a van der Waals heterostructure

TL;DR

This study investigates how interfacial bubbles in van der Waals heterostructures influence their mechanical and fracture behavior, revealing bubble growth as a key factor in layer detachment and interfacial dynamics.

Contribution

It provides new insights into the role of interfacial bubbles in the mechanical stability and fracture processes of van der Waals heterostructures using nanomechanical resonators.

Findings

Large bubbles trigger hysteretic layer detachment.

Bubble growth due to stress concentration initiates fracture.

Small bubbles do not cause delamination.

Abstract

2D van der Waals heterostructures (vdWH) can result in novel functionality that crucially depends on interfacial structure and disorder. Bubbles at the vdWH interface can modify the interfacial structure. We probe the dynamics of a bubble at the interface of a graphene-hBN vdWH by using it as the drumhead of a NEMS device because nanomechanical devices are exquisite sensors. For drums with different interfacial bubbles, we measure the evolution of the resonant frequency and spatial mode shape as a function of electrostatic pulling. We show that the hysteretic detachment of layers of vdWH is triggered by the growth of large bubbles. The bubble growth takes place due to the concentration of stress resembling the initiation of fracture. The small bubbles at the heterostructure interface do not result in delamination as they are smaller than a critical fracture length. We provide insight into frictional dynamics and interfacial fracture of vdWH.