Fig. 7

Schematic diagram of the growth model of GaN films on nitrogen-plasma-treated graphene. a AlN nucleation islands on untreated graphene. The nucleation orientation shows a random in-plane orientation. b Direct growth of graphene on SiC substrate. c As-grown graphene after nitrogen-plasma pre-treatment. The C–N-related dangling bonds were formed on nitrogen-plasma-treated graphene, and the gray, red, and blue spheres represent the C, pyrrolic N, and pyridinic N atoms, respectively. d AlN nucleation islands on nitrogen-plasma-treated graphene. The nucleation orientation of AlN on the etched graphene region continues the orientation of SiC substrate, which is a single crystal with c-axis orientation. e Epitaxial growth of continuous GaN films on AlN buffer. f Cross-sectional HAADF-STEM image of the interface at AlN/graphene/SiC