Nitrogen-Doped Single Crystal Diamond for Magnetometry
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Solution Overview
Problem
Existing diamond-based magnetometers face challenges in optimizing material-related aspects to achieve high sensitivity, as the concentration of negatively charged nitrogen-vacancy defects (NV−) and decoherence time (T2′) are interrelated, leading to limitations in magnetometry figure of merit (FOM).
Innovation Solution
Developing a single crystal diamond material with optimized growth and treatment processes, including high nitrogen content CVD diamond recipes and specific irradiation and annealing schemes, to independently control the concentrations of NV− and T2′, thereby enhancing the magnetometry figure of merit (FOM).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the concentration of negatively charged nitrogen-vacancy defects (NV−) is increased to improve magnetometry sensitivity, then the magnetometry figure of merit (FOM) improves, but the decoherence time (T2′) decreases
Solution Approach 1:
The patent applies parameter changes by systematically varying multiple material parameters including nitrogen concentration, irradiation dose, annealing temperature, and annealing time to independently control both NV− concentration and decoherence time. This multi-parameter optimization approach enables achieving high magnetometry FOM by finding the optimal balance between these two interrelated parameters
Solution Approach 2:
The patent employs preliminary action through pre-irradiation treatment before annealing, where the diamond material is first irradiated to create vacancies and defect structures, then subsequently annealed to transform these into NV− centers with desired concentrations. This two-step preliminary preparation enables better control over the final defect concentration and coherence properties
2Quantity of substance
If high nitrogen content CVD diamond recipes are used to increase NV− concentration, then the magnetometry FOM improves, but the material design flexibility and control over T2′ are reduced
Solution Approach 1:
The patent segments the diamond material into regions with different nitrogen concentrations and defect densities by controlling growth conditions and irradiation parameters. This allows creating zones optimized for different functions: high NV− concentration regions for sensitivity and lower nitrogen regions for maintaining long coherence times
Solution Approach 2:
The patent creates composite diamond structures with varying nitrogen contents and defect configurations within the same crystal. By combining regions with different properties (high NV− concentration vs. long T2′), the material achieves both high sensitivity and design flexibility for different magnetometry application requirements
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Achieves a high magnetometry figure of merit (FOM) of at least 2, with flexibility in material design, allowing for improved sensitivity and controllable properties suitable for various magnetometry applications.
Implementation Method 1
single substitutional nitrogen defects (Ns) which transfer their charge to the neutral nitrogen-vacancy defects (NV0) to convert them into the negatively charged nitrogen-vacancy defects (NV−)
Implementation Method 2
formation after diamond material synthesis from native nitrogen defects incorporated during the growth process by irradiating the synthetic diamond material to introduce vacancy defects
Implementation Method 3
formation after diamond material synthesis from native nitrogen defects incorporated during the growth process by post-growth annealing the material at a temperature (around 800° C.) which causes migration of the vacancy defects through the crystal lattice
Implementation Method 4
Its electronic structure comprises emissive and non-emissive electron spin states which allows the electron spin state of the defect to be read out through photons
Implementation Method 5
When an external magnetic field or strain field is applied, the degeneracy of the spin sublevels ms=±1 is broken via Zeeman splitting
Data Source
AI summary
A single crystal diamond material comprising: neutral nitrogen-vacancy defects (NV0); negatively charged nitrogen-vacancy defects (NV−); and single substitutional nitrogen defects (Ns) which transfer their charge to the neutral nitrogen-vacancy defects (NV0) to convert them into the negatively charged nitrogen-vacancy defects (NV), characterized in that the single crystal diamond material has a magnetometry figure of merit (FOM) of at least 2, wherein the magnetometry figure of merit is defined by (I) where R is a ratio of concentrations of negatively charged nitrogen-vacancy defects to neutral nitrogen-vacancy defects ([NV−]/[NV0]), [NV−] is the concentration of negatively charged nitrogen-vacancy defects measured in parts-per-million (ppm) atoms of the single crystal diamond material, [NV0] is a concentration of neutral nitrogen-vacancy defects measured in parts-per-million (ppm) atoms of the single crystal diamond material, and T2′ is a decoherence time of the NV− defects, where T2′ is T2* for DC magnetometry or T2 for AC magnetometry.