Fig. 2

Creation yields and coherence times. a Ratio of created fluorescent spots to implanted C₅N₄H_n ions from a total measured area of 10,400 μm². The numbers of single, double, and triple NV centres were 1,589 (22.3%), 244 (3.4%), and 9 (0.1%), respectively. The closed circles and solid line represent the best fitting Poisson distribution (λ = 0.30). The fitting was conducted in a linear scale and the plotting is represented in a logarithmic scale. b Creation yield depends on the ion acceleration energy. The closed circle shows the creation yield of the NV centres in this study, and the open symbols show the data from previous studies. It is clear that the creation yield of 7.4% achieved in this study is higher than those reported from previous studies. c Histogram of the coherence time, T_2,Hahn, measured by Hahn echo pulse sequence shown next to the histogram. The hatched, dotted, and open bars show the T_2,Hahn values observed from the single, double, and triple NV centres, respectively. The total numbers of measured T₂,_Hahn for single, double, and triple NV centres were 38, 13 (26 NVs), and 9 (19 NVs). The maximum T_2,Hahn in this work was 428 µs. d Comparisons of maximum T_2,Hahn in this work with those from the previous studies with various ion energies