Electrically Inert h-BN/Bilayer Graphene Interface in All-Two-Dimensional Heterostructure Field Effect Transistors

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Bilayer graphene field-effect transistors (BLG-FETs) are sensitive to potential fluctuations from charged impurities in gate stacks.
• Van der Waals heterostructures with hexagonal boron nitride (h-BN) offer superior electrical transport but have unrevealed interface properties.
• Parasitic capacitance has hindered the study of carrier response at h-BN/BLG heterointerfaces.

Purpose of the Study:

• To investigate and reveal the carrier response properties at the h-BN/BLG heterointerface.
• To demonstrate the suppression of potential fluctuations and off-current in BLG-FETs.
• To pave the way for future bilayer graphene electronics applications.

Main Methods:

• Fabrication of an all-two-dimensional heterostructure BLG-FET on a quartz substrate.
• Characterization of potential fluctuations and off-current at low temperatures (20 K).
• Capacitance measurements to analyze electron trap/detrap response at the heterointerface.

Main Results:

• Achieved a significant reduction in potential fluctuations to approximately 1 meV.
• Suppressed the off-current to the measurement limit with a small band gap of approximately 90 meV at 20 K.
• Demonstrated that electron trap/detrap response at the heterointerface is undetectable within the measurement frequency range.

Conclusions:

• The developed all-2D heterostructure BLG-FET exhibits significantly reduced potential fluctuations.
• The h-BN/BLG heterointerface is electrically inert, suppressing carrier trapping and enabling low off-current.
• This work provides a foundation for realizing advanced bilayer graphene electronic devices.