Vertical transport in graphene-hexagonal boron nitride heterostructure devices

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Emerging research focuses on vertical heterostructures of 2D materials for advanced electronics.
• Graphene and hexagonal boron nitride (h-BN) are key materials in these heterostructures.

Purpose of the Study:

• To investigate the tunneling properties of single- and double-barrier structures using graphene and related 2D materials.
• To understand the influence of graphene interlayers on tunneling phenomena in these heterostructures.

Main Methods:

• Density functional theory (DFT) calculations were employed to model quantum mechanical tunneling.
• Multiscale simulations were utilized to analyze device characteristics, including current-voltage (I-V) behavior.
• Structures investigated included single barriers and double barriers separated by graphene.

Main Results:

• Tunneling through single barriers showed weak energy dependence.
• Double barriers with a graphene interlayer did not exhibit resonant tunneling.
• Graphene layers acted as phase randomizers, causing double barriers to behave as two independent single barriers in series.
• Simulated I-V characteristics mimicked experimental resonant tunneling diode behavior in single-barrier structures.
• Peak current in simulations was achieved with optimal density of states matching between graphene electrodes.

Conclusions:

• Graphene interlayers fundamentally alter tunneling dynamics in 2D material heterostructures by suppressing resonant tunneling.
• The observed behavior in double-barrier structures suggests a design principle for novel electronic devices.
• Achieving specific current-voltage characteristics relies on matching the electronic states of graphene contact regions.