Engineering preferentially-aligned nitrogen-vacancy centre ensembles in CVD grown diamond

Area of Science:

• Quantum sensing
• Materials science
• Diamond

Background:

• Nitrogen-Vacancy (NV) centers in diamond are promising quantum sensors.
• Improving their sensitivity and coherence time is crucial for advanced applications.
• Controlled fabrication and post-processing are key to optimizing NV center properties.

Purpose of the Study:

• To develop a method for enhancing the magnetic field sensitivity of NV centers.
• To investigate the effects of high-temperature annealing on NV center properties and alignment.
• To quantify the improvements in sensitivity and coherence time.

Main Methods:

• Fabrication of preferentially aligned NV centers in 12C-enriched diamond using Plasma Enhanced Chemical Vapor Deposition (PECVD).
• Quantitative analysis of NV center concentration via confocal microscopy.
• High-temperature vacuum annealing (1500°C) to convert substitutional nitrogen into NV centers and improve coherence time.

Main Results:

• Achieved a threefold enhancement in magnetic field sensitivity.
• Increased the coherence time of NV center electron spins to 40 μs.
• Observed a 34% loss in the preferential alignment of NV centers after annealing.

Conclusions:

• High-temperature annealing is an effective method for improving NV center sensitivity and coherence time.
• The trade-off between enhanced spin properties and reduced alignment needs consideration for sensor design.
• This technique offers a pathway to more sensitive diamond-based quantum sensors.