Misfit Strain-Induced Buckling for Transition-Metal Dichalcogenide Lateral Heterostructures: A Molecular Dynamics Study

Abstract

Molecular dynamics simulations are performed to investigate the misfit strain-induced buckling of the transition-metal dichalcogenide (TMD) lateral heterostructures, denoted by the seamless epitaxial growth of different TMDs along the in-plane direction. The Stillinger–Weber potential is utilized to describe both the interaction for each TMD and the coupling between different TMDs, i.e., $\hbox {MX}_{2}$ (with $\mathrm{M}=\hbox {Mo}$, W and $\mathrm{X}=\hbox {S}$, Se, Te). It is found that the misfit strain can induce strong buckling of the freestanding TMD lateral heterostructures of large area, resulting from the TMDs’ atomic-thick nature. The buckling phenomenon occurs in a variety of TMD lateral heterostructures of different compositions and in various patterns. Our findings raise a fundamental mechanical challenge for the structural stability of the freestanding TMD lateral heterostructures.

Appendix: Modification for LAMMPS

We point out one necessary modification for the three-body SW potential implemented in LAMMPS. More details on this modification can be found from our earlier work [65]. Overall, the modification is done in two steps.

• 1) First, find the following line in the pair sw.cpp source file,

  delcs = cs - paramijk->costheta;

• 2) Second, insert the following new lines after the above line,

if(fabs(delcs) <= 0.25)

{

delcs = delcs; }

else if(fabs(delcs) < 0.35)

{

delcs = delcs * (0.5+0.5*sin(3.142*(delcs-0.25)/(0.35-0.25)+0.5*3.142));

}

else

{

delcs = 0.0;

}

Then, recompile the LAMMPS package. The recompiled LAMMPS executable file can be used to simulate materials with inequivalent angles around each atom (like TMDs in the present work) using the SW potential. This modification does not affect other simulations with LAMMPS.