Speaker
Description
Monocrystalline diamonds (MCD) embedded with color centers have emerged as promising candidates for applications in quantum optics, namely sensing. Specifically, negatively-charged silicon vacancy centers (SiV) stand out as ideal due to their narrow zero phonon line (ZPL) at 738 nm, coupled with a high Debye-Waller factor of up to 70 %. However, their application remains hindered by the fabrication challenges associated with producing high-quality, dense, homogeneous SiV ensembles.
The plasma-enhanced chemical vapor deposition (PE-CVD) process can be employed to grow nearly relaxed ensembles of high densities (up to 1013 cm-3). We employed a slow growth rate (tens of nm/hour) on pre-selected MCD substrates, aiming to achieve high homogeneity of centers and low stress in the diamond matrix. The concentration of SiH4 gas, used as a Si precursor, was varied in order to investigate its effects on the optical properties of SiVs.
To further optimize the material quality, the grown samples were subsequently subjected to high-temperature annealing in the range of 600–1200 °C. High-temperature annealing is a widely used post-processing technique that promotes the formation of SiV centers through vacancy diffusion and pairing with silicon atoms. We observe a pronounced increase in the absolute ZPL room-temperature photoluminescence intensity with increasing annealing temperature, accompanied by enhanced low-temperature ZPL splitting. Pump–probe spectroscopy and PL decay measurements were further employed to investigate the time-resolved processes, while Raman spectroscopy was employed to characterize possible structural changes in the material.
