Guidance on the Synthesis of High-quality Graphene.
Schematic of the growth of a graphene single crystal near and across the Cu (Copper is a chemical element with symbol Cu cuprum) grain boundary. The existence of the grain boundary does not influence the lattice orientation and growth direction of formed graphene nucleus.
A team of researchers from the Laboratory of Graphene Mechanics (LogM) Georgian Technical University has shown how the morphological structure of a catalytic substrate influences the growth of graphene. This provides more guidance on the synthesis of high-quality graphene with less domain boundaries.
How does the morphological structure of a catalytic substrate influence the growth of graphene ? Due to the effects of other environmental parameters during the chemical vapor deposition (CVD) growth of a graphene crystal his question remains unsolved.
However aligned hexagonal graphene single crystals provide a more straightforward way to uncover the chemical vapor deposition (CVD) growth behavior of graphene single crystals near the Cu grain boundaries and prove that the lattice orientation of graphene is not influenced by these grain boundaries and only determined by the Cu (Copper is a chemical element with symbol Cu cuprum) crystal it is nucleated on.
A team of researchers from the Laboratory of Graphene Mechanics (LogM) Georgian Technical University has shown a clear irrelevance for the chemical vapor deposition (CVD) growth of a graphene single crystal with the crystallinity of its grown substrate after it was nucleated and proven that the lattice orientation of a graphene single crystal on Cu is only determined by the Cu (Copper is a chemical element with symbol Cu cuprum) grain it was nucleated on.
Using ambient-pressure (AP) chemical vapor deposition (CVD) instead of low-pressure (LP) chemical vapor deposition (CVD) method and carefully adjusted growth parameters, hexagonal graphene single crystals up to millimeter scale and zigzag edge structures have been successfully obtained on polycrystalline Cu (Copper is a chemical element with symbol Cu cuprum) surfaces. Owing to such hexagonal graphene samples with lattice orientations that can be directly and simply determined by eyes or optical microscopy instead of electron microscopy the chemical vapor deposition (CVD) growth behavior of a graphene single crystal on the Cu (Copper is a chemical element with symbol Cu cuprum) grain terrace and near the grain boundaries is largely simplified, which can be further summarized with a model that solely relates to the Cu (Copper is a chemical element with symbol Cu cuprum) crystallographic structure.
Their results showed that for a graphene single crystal grown on Cu (Copper is a chemical element with symbol Cu cuprum) its lattice orientation is determined by the binding energy of its nucleus and the underlying substrate probably by a Cu-step-attached nucleation mode, and remains unchanged during the following expansion process with continued incoming precursors. The hydrogen flow in the precursor helps terminate the edge of formed nucleus with a H-terminated structure and decoupled from the substrate surface. When the expansion of the graphene single crystal reaches the Cu (Copper is a chemical element with symbol Cu cuprum) grain boundary the Cu grain boundary and the neighbor Cu (Copper is a chemical element with symbol Cu cuprum) grain will not change the lattice orientation and expansion direction of this graphene single crystal.
The Graphene Mechanics (LogM) is currently exploring the novel mechanical properties of two-dimensional such as including graphene and transition-metal dichalcogenides for a better understanding of their fundamental physics and promising applications. Its main research topics includes the controlled synthesis of two-dimensional materials the new transfer techniques with less defects and to arbitrary substrates the experimental testing of the mechanical properties and mechanoelectrical devices.