Barrier-assisted ion beam synthesis of transfer-free graphene on an arbitrary substrate

In distinction to the generally utilized chemical vapor deposition (CVD) synthesis that leads to multilayer graphene growth by carbon (C) synthesis from nickel (Ni), we proposed a controllable strategy to synthesize graphene on an arbitrary substrate through ion implantation technology, where the layer number of the obtained graphene film is accurately controlled by the corresponding dose of implanted C ions. To be specific, an oxide layer (NiO) was introduced as the barrier to prevent implanted C atom precipitation at the surface but at the interface. Various unusual substrates (such as sapphire, glass, SiO₂, and Si), in terms of traditional CVD, have been utilized for growing high-quality graphene. Employing the as-grown graphene/Si, Schottky junction-based photodetectors with high responsivity (63 mA W^-1) and high detectivity (∼1.4 × 10¹⁰ cm Hz^1/2W^-1) at 1550 nm are demonstrated without requiring any post-transfer process, thus avoiding additional contaminations, complexities, and costs during device fabrications. Our works afford a versatile technique for growing graphene on arbitrary substrates, with controllable layer numbers and transfer-free optoelectronic device fabrications, thus accelerating their further practical applications in electro-optical devices.