Localized fabrication and integration of color centers in diamond by FIB

Color centers (CCs) of group IV elements coupled to vacancies in diamond are emerging as robust solid‐state single-photon sources with exceptional optical and spin properties, making them highly attractive for quantum technology applications. At Fondazione Bruno Kessler, we have developed a comprehensive fabrication platform that enables the precise creation and integration of Group-IV defect centers, particularly silicon-vacancy (SiV) and germanium-vacancy (GeV) centers, with formation yields matching those reported in the literature. In our approach focused ion beam (FIB) tool equipped with a liquid metal alloy ion source (LMAIS) was used to implant Ge and Si ions at extremely low fluences. This mask-less, highly localized process allows us to form shallow CCs with nanometer precision while minimizing collateral lattice damage. Furthermore, we have proved the possibility to finely align and fabricate nanopillar arrays in correspondence the implanted CCs, further improving the out-coupling efficiency. In addition, we integrate these emitters into prefabricated nanostructures like solid immersion lenses (SILs), achieving a high alignment accuracy, essential for enhanced photon extraction. Finally, by inducing lattice damage by ion implantation, we form localized graphitic regions that serve as ohmic contacts on the diamond substrate. These conductive features are key elements for the development of integrated electronic and photonic diamond-based devices. In this work we will present a summary of these activities to produce and integrate high-quality, localized diamond CC for scalable quantum photonic applications.