Atomic-scale probing of defect-assisted Ga intercalation through graphene using ReaxFF molecular dynamics simulations

Toward a Mechanistic Understanding of the Formation of 2D-GaNx in Epitaxial Graphene

“…Even though defects in the graphene layer are effective to enhance intercalation, the nature of the defects and their impact on intercalation and chemical conversion of intercalants has remained elusive. Two recent studies using reactive force fields (ReaxFF) and density functional theory (DFT) , show that Ga intercalation through mono- and divacancies is kinetically hindered while larger size defects (>divacancy) significantly lower the kinetic barrier encountered during Ga penetration through graphene and, by consequence, lower the growth temperature required for the 2D-Ga fabrication.…”

Discovering atomistic pathways for supply of metal atoms from methyl-based precursors to graphene surface

“…9 We note that other classical molecular dynamics simulations supported by experiments indicate plausible atomistic pathways for Ga atom intercalation across extended defects in graphene. 10…”

Recent Advances in 2D Material Theory, Synthesis, Properties, and Applications

“…Therefore, ReaxFF molecular dynamics (MD) simulations are highly effective in capturing detailed chemical events, reaction pathways, and product formation during gas-phase and gas/condensed phase simulations, for systems up to ≈10 6 atoms and for time scales not accessible to first-principles based techniques. This ReaxFF potential can simulate the nucleation and growth and intercalation of 2D materials, which involves both gas-phase and surface interactions, as a function of local chemical environment, helping in predicting effective growth protocol. − It features vdW interactions which particularly enables the simulation of multilayer vdW hetero- and homostructures. , Additionally, ReaxFF provides thermodynamic and kinetic insight into fundamental solid-phase phenomena observed in 2D materials such as atomic intercalation, grain boundary (GB), defect formation and diffusion, stress induced lattice distortions, morphological evolution of 2D domains as a function of local chemical environment during the growth. Also, ReaxFF differs from the so-called “first generation” reactive force fields such as Tersoff , and Brenner by applying a significantly longer-ranged bond-order relationship, which makes it possible to achieve accurate reaction kinetics.…”

“…The nonuniformities that influence device performance can be divided in two groups: inherited during synthesis (intrinsic) and acquired during device fabrication process. Intrinsic nonuniformities include atomic impurities, lattice defects, ,, GBs, wrinkles and ruptures that result in strain, doping and/or charge transfer, often possessing variation at the nanometer scale. Acquired nonuniformities that come from the transfer process and nanofabrication can be partially eliminated by post-transfer cleaning procedures (annealing) or by using Soxhlet extractor for improving quality of transfer.…”

“…The ReaxFF framework has been successfully applied to a wide range of 2D systems 50−52 and their defect formation, growth mechanisms and characterization, as shown in the following examples. 46,52 used a combination of ReaxFF-and DFT-based simulations to study defects in graphene, which can act as pathways for Ga intercalation into the interface between graphene and SiC. The results show that the sizes of vacancy defects ranging from single carbon vacancy (SV) to multiple carbon vacancy (3 and 4 V) can affect the thermodynamic and kinetic preference of intercalant between the adsorption on graphene surface or the intercalation at the interface.…”