Micron-sized diamond particles containing Ge-V and Si-V color centers

Micron-sized diamond particles containing germanium-vacancy (Ge-V) color centers with a zero-photon line (ZPL) around 602.3 nm are successfully grown using hot filament chemical vapor deposition. The crystal morphology changes from icosahedron to truncated octahedron and decahedron, finally becomes spherical with the growth pressure increase. Due to the chamber containing Si, all diamond particles contain silicon-vacancy (Si-V) color centers. High growth pressure contributes to the formation of Ge-V and Si-V in diamonds. With prolonging growth time, the change in the full width at half maximum (FWHM) of the diamond peak is small, which shows that the concentration of Ge-V and Si-V centers nearly maintains a constant. The FWHM of the Ge-V ZPL is around 4 nm, which is smaller than that reported, suggesting that the Ge-V center has a more perfect structure. Ge-V and Si-V photoluminescence (PL) intensities increase with the prolonging growth time due to the increased diamond content and reduced content of sp²-bonded carbon and trans-polyacetylene. In summary, increasing the growth pressure and prolonging the growth time are beneficial to enhance the Ge-V and Si-V PL intensities.