Formation mechanism of SiV in diamond from unintentional silicon doping by microwave plasma chemical vapor deposition.

Silicon vacancies in diamond, one of the most promising single photon sources, is difficult to be achieved in a controlled and reproducible way due to complicated doping behavior of silicon in diamond by microwave plasma CVD. In this work, the underneath mechanism of silicon vacancies formed by unintentional silicon (The silicon source is SiO 2 from the microwave plasma CVD quartz window) doping in diamond was investigated from the view of growing surface kinetics through a series of experiments. During deposition, the addition of N 2 to the CH 4 -H 2 reaction gas mixture is beneficial to the formation of silicon vacancies in diamond from unintentional silicon doping, and the addition of a minor amount of oxygen will enhance the plasma etching. The increased number of the dangling bonds is beneficial to the formation of silicon vacancies and nitrogen vacancies in diamond, while excessive oxygen will passivation the dangling bonds and thus inhibit the formation of vacancies. Finally, the vertical distributions of the surface topography, growth rate, intensity of photoluminescence of NV and SiV color centers doped in the diamond film, are measured with high spatial resolution on growth surface, which are also related to the plasma electron temperature and density. These findings are of importance for searching of optimal growth regimes of NV and SiV doped single crystals by microwave plasma CVD. • The addition of nitrogen to the growth gas is beneficial to the formation of SiV−. • A minor amount of oxygen promotes while excessive oxygen inhibits the formation of NV− and SiV−. • The growth and distribution of NV− and SiV− in diamonds are related to the plasma on the surface of the substrate. [ABSTRACT FROM AUTHOR]