Postsynthesis of h-BN/Graphene Heterostructures Inside a STEM

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional (2D) materials offer tunable properties when combined into heterostructures.
• Controlled synthesis of lateral heterostructures with distinct domains remains a challenge.

Purpose of the Study:

• To directly observe and report the synthesis of lateral graphene/hexagonal boron nitride (h-BN) heterostructures.
• To investigate the atomic structure of the growth interface and the resulting nanostructures.
• To analyze the electronic properties and interlayer coupling in vertically stacked heterostructures.

Main Methods:

• In-situ epitaxial in-plane graphene growth from h-BN step-edges within a scanning transmission electron microscope (STEM).
• Utilized residual hydrocarbon as the carbon source for graphene growth.
• Atomic identification of the growth interface using STEM and electron energy-loss spectroscopy (EELS).

Main Results:

• Direct observation of lateral graphene growth on h-BN, forming N-C bonds at the interface.
• Successful synthesis of graphene nanoribbons connecting h-BN domains with varying twist angles.
• Formation of isolated carbon islands embedded within the h-BN layer.
• Electron energy-loss spectroscopy (EELS) revealed a robust coupling effect in vertically stacked h-BN/graphene heterostructures.

Conclusions:

• Demonstrated a novel postgrowth method for synthesizing lateral graphene/h-BN heterostructures.
• The method allows for controlled formation of graphene nanoribbons and islands on h-BN.
• The synthesized heterostructures exhibit strong electronic coupling, paving the way for novel electronic devices.