Nickel-induced in-situ nitrogen suppression in single crystal diamond growth
August21, 2025
Nickel-induced in-situ nitrogen suppression in single crystal diamond growth
A novel in-situ strategy reported to suppress nitrogen incorporation during microwave plasma chemical vapor deposition (MPCVD) growth of single-crystal diamond (SCD) by introducing nickel acetate solution via gas bubbling.
By optimizing precursor concentration and carrier gas flow, nitrogen impurities are reduced to <5 ppb, while silicon-related defects fall below the photoluminescence detection limit.
It is proposed that reactive nitrogen species combine with nickel to form volatile nitrides, which are subsequently removed from the plasma. Electron paramagnetic resonance confirms the ultra-low nitrogen content without detectable nickel residues, and Raman and optical microscopy reveal preserved crystalline quality and step-flow growth.
Device characterization demonstrates a significant improvement in UV photodetectors: the dark current decreases, the responsivity reaches 244 A/W, the rejection ratio approaches 10⁷, and sensitivity improves by three orders of magnitude. Simulations further reveal that shallow nitrogen-related defect levels (Ec − 0.6 eV) dominate the dark current, while deep levels (Ec − 2.5 eV) govern photocurrent behavior.
Compared with previous approaches requiring complex chambers, oxygen addition, or toxic tungsten precursors, this nickel-mediated method is simple, scalable, and environmentally benign. The results establish an effective pathway toward electronic-grade diamond and high-performance UV photodetectors
