Nitrogen concentration control during diamond growth for NV^- centre formation

Area of Science:

• Quantum physics
• Materials science
• Solid-state physics

Background:

• Nitrogen-vacancy (NV-) centers in diamond are crucial for quantum technologies like magnetic sensing.
• Achieving high sensitivity requires precise control over nitrogen concentration in diamond crystals.

Purpose of the Study:

• To demonstrate precise control of nitrogen concentration in diamond using High-Pressure/High-Temperature (HPHT) and Chemical Vapor Deposition (CVD) methods.
• To investigate the relationship between nitrogen concentration and the coherence time of NV- centers.

Main Methods:

• Controlled nitrogen incorporation during HPHT synthesis using titanium or aluminum as getters.
• Controlled nitrogen incorporation during CVD by adjusting the nitrogen to carbon flow rate ratio.
• Formation of NV- centers via electron beam irradiation and characterization of electron spin coherence time (T2).

Main Results:

• Nitrogen concentration in HPHT diamonds decreased semi-logarithmically with increasing getter material content.
• Nitrogen concentration in CVD diamonds increased linearly with the nitrogen to carbon flow rate ratio.
• NV- center coherence time (T2) was inversely proportional to nitrogen concentration, with no significant difference between HPHT and CVD diamonds.

Conclusions:

• Both HPHT and CVD methods offer precise control over nitrogen concentration in diamond.
• Nitrogen concentration directly influences the coherence time of NV- centers, impacting sensor performance.
• These findings are vital for optimizing diamond-based quantum sensors.