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.