CVD Diamond NV- Defect Fabrication for Quantum Sensing

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Solution Overview

Problem

Near surface nitrogen-vacancy (NV-) defects in synthetic diamond materials formed via nitrogen ion implantation and annealing exhibit shorter spin coherence times compared to native NV- defects in bulk high purity single crystal CVD diamond materials.

Innovation Solution

A method of fabricating diamond components by growing a single crystal CVD diamond layer with a smooth, as-grown surface of low roughness, implanting nitrogen without polishing or etching, and annealing to form NV- defects, which results in longer spin coherence times for near surface NV- defects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If nitrogen ion implantation is performed on polished or etched diamond surfaces to form NV- defects, then NV- defects can be created, but the spin coherence time is reduced due to surface damage

Engineering Contradiction:

Improvespin coherence timeVSAvoidsurface damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by growing a smooth diamond surface layer via CVD before nitrogen implantation. This pre-formed smooth surface (with Ra < 100 nm) prevents surface damage during subsequent implantation and annealing processes, thereby preserving spin coherence time while enabling NV- defect formation near the surface.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent converts the typically harmful effect of surface polishing and etching (which cause damage) into a beneficial process by using CVD growth to create a smooth surface. This inverted approach transforms the usual harmful surface preparation into a protective measure that maintains crystal integrity while enabling defect formation.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Manufacturing precision

If polishing or etching is performed on the diamond surface before nitrogen implantation, then the surface can be smoothed, but damage is introduced that reduces NV- spin coherence time

Engineering Contradiction:

Improvesurface smoothnessVSAvoidspin coherence time

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent replaces mechanical surface preparation methods (polishing and etching) with a chemical vapor deposition process. The CVD growth of diamond layers naturally produces smooth surfaces (Ra < 100 nm) without the mechanical damage inherent in traditional polishing or chemical damage from etching, thus achieving both surface smoothness and preservation of spin coherence.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If nitrogen is implanted into as-grown CVD diamond surfaces with low roughness, then NV- defects form with long spin coherence times, but the surface must be grown with controlled roughness first

Engineering Contradiction:

Improvespin coherence timeVSAvoidfabrication process steps

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the surface smoothing function and the defect formation function into a single integrated process. By controlling CVD growth parameters to produce smooth surfaces in-situ, the need for separate polishing or etching steps is eliminated, combining surface preparation and defect formation into one unified fabrication approach.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The CVD growth process serves multiple functions simultaneously: it grows the diamond layer, creates the smooth surface (Ra < 100 nm), and prepares the substrate for nitrogen implantation. This multi-functional approach eliminates the need for separate surface preparation steps while achieving the desired surface quality for long spin coherence.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

The approach leads to near surface NV- defects with extended spin coherence times, suitable for nanomagnetometry and quantum information processing applications, while maintaining a low surface damage and defined position of NV- defects.

Implementation Method 1

growing a single crystal CVD diamond layer

Methodology Applied

Scientific EffectChemical Vapour Deposition: Chemical Vapour Deposition

Implementation Method 2

implanting nitrogen into said as-grown growth face

Methodology Applied

Scientific EffectIon Implantation: Ion Implantation

Implementation Method 3

annealing the single crystal CVD diamond layer to cause migration of vacancy and/or nitrogen defects

Methodology Applied

Scientific EffectAnnealing: Annealing

Implementation Method 4

cause migration of vacancy and/or nitrogen defects within the single crystal CVD diamond layer

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentEP3071736B1Diamond components for quantum imaging, sensing and information processing devices

Publication Date: 2021.11.17 ELEMENT SIX TECH LTD

Figure 1(A)~1(F)
Figure 2(A)~3
Figure 4

AI summary

A single crystal CVD diamond component comprising: a surface, wherein at least a portion of said surface is formed of as-grown growth face single crystal CVD diamond material which has not been polished or etched and which has a surface roughness Ra of no more than 100 nm; and a layer of NV- defects, said layer of NV- defects being disposed within 1 μm of the surface, said layer of NV- defects having a thickness of no more than 500 nm, and said layer of NV- defects having a concentration of NV- defects of at least 105 NV-/cm2.