Highly Oriented Epitaxial Hexagonal Boron Nitride Multilayers on High-Temperature-Resistant Single-Crystal Aluminum...

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Physics

Background:

• Epitaxy of hexagonal boron nitride (hBN) multilayers on dielectric wafers is crucial for advanced applications but faces significant challenges.
• Achieving high-quality, oriented hBN films directly on dielectrics is a persistent hurdle in materials science.

Purpose of the Study:

• To develop an industry-compatible method for growing highly oriented hBN multilayers on dielectric substrates.
• To investigate the role of aluminum nitride (AlN) as a substrate for hBN epitaxy and annealing.
• To characterize the structural and optical properties of the grown hBN films and their embedded quantum emitters.

Main Methods:

• Metalorganic vapor phase epitaxy (MOVPE) was employed to grow hBN multilayers.
• High-temperature annealing (up to 1800 °C) was performed on hBN grown on AlN/sapphire and bulk AlN substrates.
• Structural alignment and optical properties, including single photon emission centers, were analyzed.

Main Results:

• Highly oriented hBN multilayers were successfully grown on single-crystal AlN/sapphire and bulk AlN substrates.
• The AlN (0001) surface provided a crystallographically commensurate and thermally stable template for hBN epitaxy.
• The resulting hBN films exhibited superior out-of-plane and in-plane alignments, with record-narrow wavelength distributions for single photon emission centers (578 ± 5 nm) and small zero-phonon linewidths (down to 1.44 meV).

Conclusions:

• An industry-compatible method for producing large-area, highly oriented hBN multilayers on dielectrics was established.
• The high uniformity and controlled properties of the hBN films, evidenced by the narrow emission spectra of quantum emitters, are promising for device applications.
• This work paves the way for the integration of high-quality hBN in future electronic and photonic devices.