This study introduces two CVD-based approaches for fabricating fluorescent nanodiamonds (NDs) with optically active silicon-vacancy (SiV) color centers: bottom-up (BU) and top-down (TD) methods. The BU approach generates nanoporous diamond films with a core−shell structure, while the TD method employs molten-salt thermal etching to create uniform porous structures from nanocrystalline diamond films. Ultrasonic disintegration of both porous films produced NDs ranging from 40 to 500 nm. Photoluminescence measurements confirmed SiV centers (738 nm) in all NDs. Temperature-resolved spectroscopy shows the potential of the fabricated NDs for nano thermometry over a wide range of temperatures up to 100 C. The presented BU and TD methods offer significant advantages over existing techniques, including streamlined production processes, high-yield ND synthesis with tailored properties, and the potential for scalable, cost-effective manufacturing.
