Highly Oriented Epitaxial Hexagonal Boron Nitride Multilayers on High‐Temperature‐Resistant Single‐Crystal Aluminum Nitride (0001)

The epitaxy of high‐quality hexagonal boron nitride (hBN) multilayers on dielectric wafers is essential for hBN applications but remains challenging. Herein, highly‐oriented hBN multilayers grown on single‐crystal aluminum nitride (AlN)—AlN on sapphire and bulk AlN substrates—via metalorganic vapor phase epitaxy and high‐temperature annealing is reported. Hexagonal AlN (0001) not only provides a crystallographically commensurate base for hBN epitaxy but is thermally stable for hBN annealing up to 1800 °C, enabling the first instance of large‐area multilayer hBN with both superior out‐of‐plane and in‐plane alignments grown directly on dielectrics using a fully industry‐compatible approach. Elevated temperatures also reduce carbon and allow control over the separation of related single photon emission centers in hBN. These centers exhibit a record‐narrow wavelength distribution (578 ± 5 nm) with small zero‐phonon linewidths down to 1.44 meV, indicating the high uniformity of the achieved multilayer hBN films. This work paves an industry‐compatible way toward producing highly‐oriented homogeneous hBN multilayers on dielectrics, promising for future device and integration applications.