  Conceptual 2D group III nitrides and oxides (e.g., 2D InN and 2D InO) in
heterostructures with graphene have been realized by metalorganic chemical
vapor deposition (MOCVD). MOCVD is credited with being central to fabrication
of established semiconductor materials and by purpose for an advance in
emergent semiconductor materials at the 2D limit. A defining characteristic of
MOCVD is the employment of metalorganic precursors such as trimethyl-indium,
-gallium, and -aluminum, which contain (strong) metal-carbon bonds. Mechanisms
that regulate MOCVD processes at the atomic scale are largely unknown. Here, we
employ density-functional molecular dynamics -- accounting for van der Waals
interactions -- to locate reaction pathways responsible for dissociation of
trimethylindium (TMIn) precursor in the gas phase as well as on top-layer and
zero-layer graphene. The simulations reveal how collisions with hydrogen
molecules, intramolecular or surface-mediated proton transfer, and direct
TMIn/graphene reactions assist TMIn transformations, which ultimately enables
delivery of In monomers, or InH and CH3In admolecules, on graphene. Results
presented also show how TMIn/H2 reactions on graphene, or in the gas phase,
lead to formation of methane, ethane, propane, ethene hydrocarbons, and atomic
hydrogen. This work provides knowledge for understanding thin-film nucleation
and intercalation mechanisms at the atomic scale and for overcoming challenges
in integration of 2D materials and graphene heterostructures in technology.
