Micron-sized diamond particles containing Ge-V and Si-V color centers**Project supported by the National Natural Science Foundation of China (Grant Nos. 50972129 and 50602039), the Natural Science Foundation of Zhejiang Province, China (Grant Nos. LQ15A040004 and LY18E020013), the International Science Technology Cooperation Program of China (Grant No. 2014DFR51160), the National Key Research and Development Program of China (Grant No. 2016YFE0133200), European

Abstract

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.