▎ 摘　　要

GaN-based light-emitting diodes (LEDs) are extremely promising and highly efficient solid-state light sources with long lifetimes. In this study, a stress-free GaN film with optimal quality and a low density of dislocations was obtained on sapphire by embedding a sputtered AlN (S-AlN)/graphene composite buffer layer. The growth of a nucleation-enhanced dislocation-annihilation structure via S-AlN/graphene-assisted quasi-van der Waals epitaxy was proposed here. Sapphire was first sputter-coated with AlN. After transfer of a monolayer graphene onto the 25 nm S-AlN surface, a 1.9 mu m GaN thin film was grown by metal-organic chemical vapor deposition. Theoretical first-principles density functional theory calculations were performed to determine the electrostatic potential on the surface of the composite substrate. We also fabricated an UV LED that delivered a stable performance using a high-quality GaN film. Finally, the present work may provide insight into the epitaxial growth of III-N films and demonstrates that fabricating stress-free, high-quality, and transferable III-N films for solid-state lighting is achievable.