Epitaxial single-crystal hexagonal boron nitride multilayers on Ni (111).

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional (2D) materials like graphene and transition metal dichalcogenides are crucial for next-generation electronics.
• Hexagonal boron nitride (hBN) is an ideal dielectric for 2D field-effect transistors (FETs), potentially extending Moore's Law.
• Previous research lacked methods for uniform, single-crystal multilayer hBN growth, hindering its use as a substrate.

Purpose of the Study:

• To develop a method for growing wafer-scale, single-crystal multilayer hexagonal boron nitride (hBN).
• To demonstrate the potential of this high-quality hBN as a dielectric substrate for 2D semiconductor devices.

Main Methods:

• Epitaxial growth of trilayer hBN on single-crystal Ni (111) via chemical vapor deposition (CVD).
• Characterization using cross-sectional transmission electron microscopy (TEM) to analyze film structure and interlayers.
• Transfer of hBN films onto SiO2/Si wafers for device fabrication and testing.

Main Results:

• Successful growth of wafer-scale single-crystal trilayer hBN.
• Formation of a Ni23B6 interlayer between hBN and the Ni substrate during cooling, with epitaxial relationships established.
• Demonstrated hBN's effectiveness as a protective layer and its ability to reduce electron doping in MoS2 FETs when used as a dielectric.

Conclusions:

• This work presents a viable method for producing high-quality, large-area single-crystal multilayer hBN.
• The developed hBN films are suitable for use as ubiquitous substrates for 2D semiconductors.
• This advancement paves the way for improved performance and integration of 2D electronic devices.