Wafer‐Scale Self‐Limiting Epitaxy of Bernal‐Stacked Single‐Crystal Boron Nitride

Why It Matters

The breakthrough provides a practical, large‑area route to ferroelectric 2D dielectrics, unlocking higher performance and new functionality in van der Waals nanoelectronics.

Key Takeaways

• Flow-modulated MOCVD achieves self‑limiting bilayer growth.
• Ni(111) step edges enforce deterministic AB stacking.
• Wafer‑scale bBN films act as atomically thin dielectrics.
• bBN interlayer enables nonvolatile ferroelectric switching in MoS₂.
• Uniform device performance demonstrated across entire wafer.

Pulse Analysis

Controlling the stacking order of two‑dimensional crystals has long been a bottleneck for commercializing advanced nanoelectronics. In boron nitride, the Bernal (AB) configuration breaks inversion symmetry, creating an out‑of‑plane polarization that can act as a built‑in ferroelectric layer. Traditional growth methods produce mixed stacking or multilayer islands, limiting device uniformity. By exploiting monoatomic Ni step edges on Ni(111), researchers can energetically favor the AB arrangement, effectively locking the crystal into a single‑phase bilayer across a 4‑inch wafer.

The flow‑modulated epitaxy approach fine‑tunes precursor delivery, accelerating surface reactions while suppressing secondary nucleation. This self‑limiting mechanism stops growth after the second layer, guaranteeing bilayer thickness without post‑growth etching. Compared with conventional CVD or exfoliation, the method delivers reproducible, wafer‑scale films with sub‑nanometer roughness, meeting the stringent tolerances of modern semiconductor fabs. The process also integrates seamlessly with existing sapphire‑based platforms, reducing capital investment for manufacturers seeking to adopt 2D dielectrics.

When incorporated as an ultrathin interlayer in top‑gated MoS₂ transistors, the bBN dielectric not only reduces charge‑trap scattering but also provides a reversible polarization state that toggles the channel conductance. This nonvolatile switching eliminates the need for external memory elements, paving the way for ultra‑low‑power logic and neuromorphic circuits. As the industry pushes toward heterogeneous integration of 2D materials, scalable, phase‑controlled bBN offers a compelling solution for high‑performance, energy‑efficient devices, positioning it as a key enabler for the next generation of van der Waals electronics.