Nitrogen-driven plasma modulation for tuning silicon-vacancy formation in diamond.

Silicon-vacancy (SiV) centers in diamond are promising for quantum photonics due to their narrow zero-phonon line and excellent photonic properties. Here, we demonstrate controlled growth of delta-doped SiV layers in nanocrystalline diamond films by a single-step microwave plasma chemical vapor deposition growth process. By manipulating nitrogen flow during growth, we achieved a uniform layer of SiVs in diamond while maintaining consistent microstructural properties throughout the film. While a correlation between microstructural change and doping density is observed, optical emission spectroscopy analysis reveals that the mechanism between the two processes is different. Atom probe tomography confirms the uniform distribution of silicon atoms in the diamond matrix, even at concentrations as high as 3.6 × 10²¹ cm^-3. The approach shows promise for the precise tuning of the layer thickness and doping concentration, and offers a scalable approach for creating high-quality SiV layers in diamond, advancing their integration into nanophotonic cavities for quantum technologies.