Integration of germanium-vacancy single photon emitters arrays in diamond nanopillars

The nanoscale fabrication of μm-spaced single-photon emitter arrays is crucial for the development of integrated photonic chips. We report on the fabrication and systematic characterization of germanium-vacancy (GeV) color centers arrays in diamond obtained upon ion implantation at the nanoscale. Ge2+ ion implantations at 35 keV and 70 keV energies were carried out using a focused ion beam (FIB) equipped with a liquid metal alloy ion source. The arrays of emitters are subsequently aligned to ø300 nm nanopillar waveguiding structures, fabricated using a combination of electron-beam lithography and plasma etching. The photon collection efficiency and photoluminescence (PL) signal-to-background ratio increased by a factor 8 with respect to the unstructured sample. The photophysical properties of the GeV emitters fabricated by this approach were unaltered with respect to those found in unprocessed diamond. The efficiency of the overall manufacturing process to fabricate individual GeV centers was assessed. Up to 33% of the fabricated nanopillars, depending on ion implantation parameters, were found to contain single emitters.