▎ 摘　　要

We report the selective-area heteroepitaxial growth of hexagonal boron nitride (h-BN) on graphene layers using catalyst-free chemical vapor deposition. For both catalyst-free and selective-area growth, exfoliated graphene layers were irradiated with a focused ion beam to generate nucleation sites on the inert graphene surface. A high-quality, ultrathin h-BN micropattern array was selectively grown only on the patterned region of graphene using borazine, ammonia, and nitrogen without any metal catalyst. The crystal structure and microstructural properties of h-BN grown on graphene were investigated using synchrotron radiation x-ray diffraction and transmission electron microscopy, respectively. The catalyst-free growth mechanism and heteroepitaxial relationship between h-BN and graphene layers are discussed.