Enhanced Growth of Homogeneous Multilayer Graphene on Ni(111) via Airflow Microcavity-Assisted PECVD

Abstract

Due to the perfect spin filtering at the lattice-matched multilayer graphene/ Ni(111) interface, the lattice-matched multilayer graphene/Ni(111) interface has been attracting wide interest in two-dimensional magnetic tunnel junctions (2D-MTJs). Plasmaenhanced chemical vapor deposition (PECVD) is an effective method for the growth of multilayer graphene on Ni(111) substrates. However, the uniformity of the grown multilayer graphene is limited by the high density of carbon free radicals and plasma bombardment, which often leads to island-like growth. In this article, an improved PECVD method with a glassenclosed airflow microcavity structure has been proposed for the uniform growth of multilayer graphene. The fluid simulation shows that a microairflow region can be formed inside the glassenclosed cavity, which effectively reduces the carbon density on the substrate surface and improves the growth uniformity of multilayer graphene. Various characterization results confirm the synthesis of full-coverage, better-uniform multilayer graphene on Ni(111) substrates. This high-quality multilayer graphene grown on monocrystalline ferromagnetic substrates readily can serve as barrier layers for magnetic tunnel junctions (MTJs), thus shedding light on their direct integration in next-generation applications in two-dimensional (2D) spintronic devices.