High-Temperature Ion Implantation for NV Center Formation in Diamond

Balancing yield and damage in near-surface NV engineering

For NV centers to work as quantum sensors or spin platforms, they need to be both bright and precisely placed, typically within 20 nm of the diamond surface. But hitting this sweet spot is challenging.

At room temperature, higher ion fluence can cause damage to the materials lattice around the desired NV, causing amorphization and leading to a loss in performance. The result is reduced brightness or even elimination of the photoluminescence effect altogether.

The solution lies in managing the tradeoff: maintaining enough defect density while avoiding structural breakdown

High-temperature nitrogen implantation using the QuiiN system

Nitrogen ions (N₂⁺) were implanted at 30 keV into electronic-grade CVD diamond using Tescan QuiiN, equipped with a focused iVeloce ion column and heated stage.

Implantation was carried out at both room temperature and 800 °C for comparison. Ar⁺ ions were used to mark regions with ring patterns for post-alignment. After implantation, all samples were annealed at 800 °C for one hour.

Implant depth was ~10–15 nm. NV patterning was performed with high spatial control. Characterization was done via confocal photoluminescence (PL), Raman spectroscopy, and DiamondView imaging at 80 K using 532 nm laser excitation.

Bright, Shallow NV Centers Without Crystal Damage

Room temperature implantation at high dose led to graphitization and a weaker PL signal. In contrast, the high-temperature process produced:

• 3–4× stronger NV photoluminescence
• No signs of amorphization or lattice damage
• Dense NV populations near the surface
• Consistent results across multiple patterned sites

The elevated temperature enabled dynamic lattice recovery, preventing damage accumulation even at fluences above 10¹⁴ ions/cm².

These results highlight the power of the Tescan QuiiN system for precision quantum defect engineering. In addition to NVs, the same workflow could support formation of SiV, GeV, or co-doped NV–He⁺ structures. With high-precision and full pattern control in the FIB, this approach is well suited for quantum sensing, spin physics, and photonics research.