Interfacial-Modulated Lattice-Polarity-Controlled Quasi-van der Waals Epitaxy of AIN Film

Recently, van der Waals epitaxy (vdWE) of 3D semiconductor films on 2D materials has become a pioneering technique. In this work, we present the interface bonding and nucleation mechanism of AlN on h-BN, and we systematically demonstrate the polarity manipulation of the AlN epilayer for the first time. Based on first-principles calculations, we confirm that B-O-N and B-O bonds, produced by O₂-plasma treatment, greatly facilitate the N-polarity AlN nucleation by forming B-O-Al-N and B-O-Al structures. In contrast, initial AlN directly grown on h-BN without pretreatment demonstrates an opposite Al-polarity. Initial N-polarity AlN on treated h-BN gradually converts into Al-polarity by forming oblique inversion domain boundaries (IDBs), driven by the metal-rich growth environment and the anisotropy of surface energies. Unlike the rapid polarity inversion of AlN on bare sapphire, the polarity inversion process of AlN on h-BN is greatly prolonged due to the unique interfacial atomic configuration and weak strain, which extends with a scope from 200 to 800 nm for AlN on 3 nm h-BN. Eventually, the epitaxy of stress-free AlN film with low dislocation density is realized on h-BN/sapphire. This work provides an effective strategy for polarity manipulation and quality improvement of III-nitride films and paves the way for high-performance deep-ultraviolet optoelectronic devices.