Enhanced conversion efficiency of vacancy-related color centers in diamonds grown on a patterned metal surface by chemical vapor deposition

Vacancy-related color centers in diamonds, such as nitrogen-vacancy (NV) and silicon-vacancy (SiV) centers, have good application prospects in solid-state quantum technologies. In various applications, shot noise-limited sensitivity is determined by coherence time and photoluminescence (PL) intensity, which depends on the color center density. However, the conversion efficiencies of impurity atoms to color centers are low and usually increased by electron irradiation, which destroy the lattice structure and create defects leading to decoherence. In this study, we epitaxially grew diamond layers containing color centers on surfaces coated with metal stripes. The PL intensities of NV0, NV-, and SiV- centers located directly above the metal surface were 3.27, 3.47, and 11.15 times higher than those of the diamond epitaxial region. The [N]-[NV] and [Si]-[SiV] conversion efficiencies were 63.26% and 35.68%, respectively, which were comparable to or even better than those achieved by electron irradiation. Moreover, the region above the metal exhibited a high lattice quality, longer transverse relaxation time, higher magnetic field sensitivity, and larger NV-/NV0 ratio. The findings of this study can help advance the existing research on NV-based magnetometers, biofluorescent labeling, and interfacial spin quantum memory and be potentially applied to other vacancy-related color centers, such as germanium-vacancy.

Automated summary

This study found that increasing the conversion efficiency of color centers in diamonds on metal surfaces can improve lattice quality and PL intensity, which is significant for the applications of related technologies.