Transfer-free graphene-guided high-quality epitaxy of AlN film for deep ultraviolet light-emitting diodes

Abstract

We report on quasi-van der Waals epitaxy of high-quality AlN film guided by transfer-free graphene (Gr) with low wrinkle density (LWD-Gr) on sapphire. The surface wrinkle density of LWD-Gr is greatly reduced by 94% compared to conventional Gr with high wrinkle density (HWD-Gr). Also noteworthy is that AlN nucleation islands grown on LWD-Gr exhibit better crystalline orientation consistency and more feasibility to coalesce with each other, thus forming AlN film with lower stress and dislocation density. Finally, 285 nm deep ultraviolet (DUV) light-emitting diodes are fabricated on the high-quality AlN template with LWD-Gr, which shows stronger electroluminescence intensity than its counterpart without and with HWD-Gr. The insights granted by this research pave a new pathway for improving the performance of nitride-based DUV optoelectronic devices through Gr engineering.