Achieving smooth and transferable AlN films on h-BN via in-situ dual-step preflow treatment

Abstract

Aluminum nitride (AlN) epitaxy was performed on multilayer hexagonal boron nitride (h-BN) via metalorganic vapor deposition (MOCVD) under varying in‑situ preflow conditions. A dual‑step preflow strategy—sequential NH3 followed by TMAl—was developed to obtain mechanically transferable AlN films with smooth morphology and single-crystalline quality. Contrast experiments suggest that the NH3 step enhances nucleation density, while the subsequent TMAl step suppresses mixed polarity in early growth. This fully in‑situ process replaces conventional ex‑situ surface modifications of h-BN, offering improved reproducibility and MOCVD compatibility, and benefiting the integration of transferable AlN‑based heterostructures into deep‑UV optoelectronic and high‑power electronic devices.