High-Electrical-Conductivity Multilayer Graphene Formed by Layer Exchange with Controlled Thickness and Interlayer

Area of Science:

• Materials Science
• Nanotechnology
• Condensed Matter Physics

Background:

• High-quality multilayer graphene (MLG) on diverse substrates is crucial for integrating advanced electronic devices with carbon materials.
• Existing synthesis methods often face limitations in achieving desired quality and uniformity on arbitrary substrates.

Purpose of the Study:

• To develop a robust method for synthesizing uniform MLG with controlled thicknesses on arbitrary substrates.
• To investigate the impact of synthesis parameters, specifically the Al2O3 interlayer, on MLG crystal quality and electrical properties.
• To explore the potential of MLG for advanced electronic device applications.

Main Methods:

• Utilized Ni-induced layer exchange at 800°C to synthesize MLG with thicknesses ranging from 5 nm to 200 nm.
• Introduced an Al2O3 interlayer between carbon and nickel layers to control diffusion and enhance crystal quality.
• Characterized MLG using Raman spectroscopy, transmission electron microscopy, and Hall effect measurements.

Main Results:

• Achieved significantly improved crystal quality for MLG with thicknesses ≥ 50 nm, particularly with the Al2O3 interlayer.
• Measured a Hall mobility of 550 cm²/Vs for 50 nm MLG, the highest reported for MLG directly on an insulator.
• Obtained an electrical conductivity of 2700 S/cm, surpassing that of highly oriented pyrolytic graphite synthesized at higher temperatures.

Conclusions:

• The Ni-induced layer exchange technique, optimized with an Al2O3 interlayer, enables the synthesis of high-quality MLG on arbitrary substrates.
• The developed MLG exhibits exceptional electrical properties, making it suitable for a wide range of device applications.
• This synthesis technology opens new avenues for exploring the extensive device applications of carbon materials.