Solution-Processed Dielectrics Based on Thickness-Sorted Two-Dimensional Hexagonal Boron Nitride Nanosheets.

Area of Science:

• Materials Science
• Nanoelectronics
• Surface Science

Background:

• Gate dielectrics are crucial for nanoelectronic device performance, influencing mobility, hysteresis, and power consumption.
• Hexagonal boron nitride (h-BN) is an ideal 2D dielectric due to its atomically flat and dangling bond-free surface.
• Existing liquid exfoliation methods for h-BN lack control over thickness and film quality, hindering solution-processed electronics.

Purpose of the Study:

• To develop a method for producing thickness-controlled, monodisperse h-BN inks for solution-processed electronics.
• To fabricate ultrathin h-BN dielectric films and evaluate their performance in graphene-based devices.
• To demonstrate the utility of h-BN inks as coatings to improve conventional dielectrics.

Main Methods:

• Isopycnic density gradient ultracentrifugation was used to prepare thickness-sorted h-BN inks.
• Layer-by-layer assembly was employed to create ultrathin h-BN dielectric films.
• Graphene field-effect transistors (GFETs) were fabricated using the solution-processed h-BN dielectrics.

Main Results:

• Monodisperse, thickness-sorted h-BN inks were successfully produced.
• Ultrathin h-BN dielectrics exhibited low leakage currents (3 × 10⁻⁹ A/cm² at 2 MV/cm) and high capacitances (245 nF/cm²).
• Solution-processed GFETs demonstrated negligible hysteresis and high mobilities (up to 7100 cm²/V·s).
• h-BN inks improved device performance when used as coatings on conventional dielectrics.

Conclusions:

• Isopycnic density gradient ultracentrifugation provides precise control over h-BN thickness for ink production.
• Solution-processed h-BN dielectrics enable high-performance GFETs with excellent electrical characteristics.
• This approach facilitates the integration of 2D heterostructure devices into large-area, solution-processed nanoelectronics.