Effective implantation of light emitting centers by plasma immersion ion implantation and focused ion beam methods into nanosized diamond

•Characteristics of nitrogen implantation of nanodiamond using two low ion energy ion implantation methods were compared.•Formation of complex nitrogen-related defect centers was promoted by subsequent helium implantation and heat treatments.•Depth profiles of the implanted ions and the generated vacancies were determined using SRIM calculations.•The presence of nitrogen impurity was demonstrated by Fourier-transform infrared spectroscopic measurements.•A new nitrogen related band was detected in the photoluminescence spectrum of the implanted samples that was attributed to the N3 color center in nanodiamond. Two different implantation techniques, plasma immersion ion implantation and focused ion beam, were used to introduce nitrogen ions into detonation nanodiamond crystals with the aim to create nitrogen-vacancy related optically active centers of light emission in near UV region. Previously samples were subjected to a defect creation process by helium irradiation in both cases. Heat treatments at different temperatures (750°C, 450°C) were applied in order to initiate the formation of nitrogen-vacancy related complex centers and to decrease the sp2 carbon content formed under different treatments. As a result, a relatively narrow and intensive emission band with fine structure at 2.98, 2.83 and 2.71eV photon energies was observed in the light emission spectrum. It was assigned to the N3 complex defect center. The formation of this defect center can be expected by taking into account the relatively high dose of implanted nitrogen ions and the overlapped depth distribution of vacancies and nitrogen. The calculated depth profiles distribution for both implanted nitrogen and helium by SRIM simulation support this expectation.