Nitrogen-Vacancy Color Centers Created by Proton Implantation in a Diamond

At a Glance

Metadata	Details
Publication Date	2021-02-09
Journal	Materials
Authors	Mariusz Mrózek, Mateusz Schabikowski, Marzena Mitura‐Nowak, Janusz Lekki, M. Marszałek
Institutions	Institute of Nuclear Physics, Polish Academy of Sciences, Jagiellonian University
Citations	19
Analysis	Full AI Review Included

Technical Documentation & Analysis: NV Center Creation via Proton Implantation

This document analyzes the research paper “Nitrogen-Vacancy Color Centers Created by Proton Implantation in a Diamond” to provide relevant technical specifications and highlight how 6CCVD’s advanced MPCVD diamond materials and customization services can accelerate and enhance similar quantum research and engineering projects.

Executive Summary

This study successfully demonstrates the controlled creation and characterization of Nitrogen-Vacancy (NV^-) color centers in diamond using high-energy proton implantation, a technique vital for quantum sensing applications.

Core Achievement: Creation of localized NV ensembles via 1.8 MeV proton implantation followed by 900 °C vacuum annealing in Type Ib HPHT diamond.
Localization: The method achieved a peak vacancy generation depth of approximately 20 µm, suitable for creating thin, dense NV layers required for high-sensitivity magnetometry.
Dose Dependence: Implantation doses spanning four orders of magnitude ($1.5 \times 10^{13}$ to $1.5 \times 10^{17}$ ions/cm²) were tested, demonstrating control over NV concentration.
Spin Relaxation: Longitudinal (T₁) and transverse (T₂) relaxation times were characterized, showing a decrease (T₁: 6 ms down to 1.25 ms; T₂: 2.5 µs down to 1.1 µs) with increasing dose due to enhanced dipole-dipole interactions and lattice damage.
Material Relevance: The findings guide the preparation of microscale NV sensors, emphasizing the need for high-quality diamond with precisely controlled nitrogen content and low initial defect density to maximize spin coherence.
Method Suitability: High-energy proton implantation is confirmed as a versatile technique for tailoring NV concentration profiles in thin films (0.1-10 µm sensing layers).

Technical Specifications

The following table summarizes the critical experimental parameters and results extracted from the research paper, focusing on material properties and measured spin dynamics.

Parameter	Value	Unit	Context
Initial Nitrogen Concentration ([N])	~50	ppm	Type Ib HPHT Diamond
Sample Orientation	(100)	N/A	One side polished
Sample Dimensions	3.0 x 3.0 x 0.3	mm³	Used for implantation
Implantation Particle Type	Proton (H⁺)	N/A	High-energy beam
Implantation Energy	1.8	MeV	Used for vacancy creation
Implantation Depth (Peak Vacancy)	~20	µm	Calculated via SRIM 2013 simulation
Implantation Dose Range	$1.5 \times 10^{13}$ to $1.5 \times 10^{17}$	ions/cm²	Across 8 distinct spots
Post-Implantation Annealing	900	°C	2 hours in vacuum system
Longitudinal Relaxation Time (T₁) Range	6 to 1.25	ms	Decreases with increasing dose
Transverse Relaxation Time (T₂) Range	2.5 to 1.1	µs	Decreases with increasing dose
ODMR Microwave Frequency	2.87	GHz	Used for spin manipulation

Key Methodologies

The creation and characterization of NV centers relied on precise control over material selection, implantation parameters, and post-processing thermal treatment.

Material Preparation: Use of (100)-oriented, one side polished Type Ib HPHT diamond monocrystals with an initial nitrogen concentration of approximately 50 ppm.
Proton Implantation: High-energy 1.8 MeV proton beam used to introduce vacancies. The focused spot diameter was approximately 20 µm.
Dose Variation: Implantation doses were systematically varied across eight spots, ranging from $1.5 \times 10^{13}$ to $1.5 \times 10^{17}$ ions/cm².
Thermal Annealing: Post-implantation vacuum annealing was performed at 900 °C for 2 hours to increase vacancy diffusion and stimulate the formation of NV centers by association with existing nitrogen atoms.
Spectroscopic Analysis: Confocal fluorescence microscopy was used to measure fluorescence intensity, and Raman spectroscopy was used to analyze crystal damage and NV⁰/NV^- peaks.
Spin Relaxation Measurement: Optically Detected Magnetic Resonance (ODMR) techniques, specifically the “relaxation in the dark” method (for T₁) and the Hahn spin-echo sequence (for T₂), were employed using a 2.87 GHz microwave signal.

6CCVD Solutions & Capabilities

6CCVD provides the high-specification MPCVD diamond materials and custom engineering services necessary to replicate, optimize, and scale the NV center creation methodology described in this research. Our capabilities directly address the need for high-purity, low-defect substrates and precise material customization.

Applicable Materials for NV Center Research

Research Requirement	6CCVD Material Recommendation	Technical Rationale
High Purity Base Material (Minimizing background defects)	Optical Grade Single Crystal Diamond (SCD)	Ultra-low nitrogen content (< 1 ppb) minimizes background fluorescence and maximizes T₁/T₂ coherence times, essential for high-fidelity quantum applications.
Controlled Nitrogen Source (For high NV density)	Nitrogen-Doped SCD (Controlled Doping)	We offer SCD with nitrogen concentrations precisely tailored from 1 ppm up to 100s of ppm, allowing researchers to optimize the vacancy-to-nitrogen conversion ratio.
Shallow NV Layers (For surface sensing/magnetometry)	High-Purity SCD Substrates for Overgrowth	We supply high-quality SCD substrates (up to 10 mm thick) suitable for subsequent MPCVD overgrowth of thin, highly nitrogen-doped layers (delta-doping), enabling ultra-shallow NV creation (0.1-10 µm).
Large Area Ensembles (Scaling up sensing arrays)	Polycrystalline Diamond (PCD) Wafers	PCD plates available up to 125 mm diameter, offering a cost-effective, large-area platform for ensemble NV magnetometry and wide-field imaging applications.

Customization Potential & Engineering Support

The successful implementation of proton implantation for NV creation relies heavily on precise material preparation and post-processing integration. 6CCVD offers comprehensive services to meet these demands:

Custom Dimensions and Thickness: While the paper used 0.3 mm thick samples, 6CCVD supplies SCD plates ranging from 0.1 µm to 500 µm thickness, ideal for optimizing the interaction depth of the 1.8 MeV proton beam. We provide custom laser cutting services for unique sample geometries.
Ultra-Precision Polishing: The paper utilized polished samples. 6CCVD guarantees superior surface quality, achieving Ra < 1 nm for SCD and Ra < 5 nm for inch-size PCD. This ultra-low roughness is critical for minimizing optical losses and maximizing fluorescence collection efficiency in confocal setups.
Integrated Microwave Delivery: The experiment required a loop-gap antenna structure for MW pulse delivery. 6CCVD offers in-house metalization services (Au, Pt, Pd, Ti, W, Cu) for depositing custom contact pads or antenna patterns directly onto the diamond surface, streamlining device integration.
Engineering Support: 6CCVD’s in-house PhD team specializes in material selection and optimization for quantum applications. We can assist researchers in determining the optimal initial nitrogen concentration and substrate specifications required to achieve target T₁ and T₂ relaxation times for similar NV Magnetometry and Quantum Sensing projects.
Global Logistics: We ensure reliable, global delivery of custom diamond materials (DDU default, DDP available), supporting international research efforts.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

We present an experimental study of the longitudinal and transverse relaxation of ensembles of negatively charged nitrogen-vacancy (NV−) centers in a diamond monocrystal prepared by 1.8 MeV proton implantation. The focused proton beam was used to introduce vacancies at a 20 µµm depth layer. Applied doses were in the range of 1.5×1013 to 1.5×1017 ions/cm2. The samples were subsequently annealed in vacuum which resulted in a migration of vacancies and their association with the nitrogen present in the diamond matrix. The proton implantation technique proved versatile to control production of nitrogen-vacancy color centers in thin films.

Tech Support

Original Source

DOI: https://doi.org/10.3390/ma14040833

References

2013 - Nanoscale sensing and imaging in biology using the nitrogen-vacancy center in diamond [Crossref]
2018 - Engineering bright fluorescent nitrogen-vacancy (NV) nano-diamonds: Role of low-energy ion-irradiation parameters [Crossref]
2016 - Quantum Metrology Enhanced by Repetitive Quantum Error Correction [Crossref]
2020 - Introduction to quantum optimal control for quantum sensing with nitrogen-vacancy centers in diamond [Crossref]
2009 - Diamonds with a high density of nitrogen-vacancy centers for magnetometry applications [Crossref]
2018 - Critical Thermalization of a Disordered Dipolar Spin System in Diamond [Crossref]
2014 - Microwave saturation spectroscopy of nitrogen-vacancy ensembles in diamond [Crossref]
2019 - Optically detected ferromagnetic resonance in diverse ferromagnets via nitrogen vacancy centers in diamond [Crossref]
2010 - Broadband magnetometry by infrared-absorption detection of nitrogen-vacancy ensembles in diamond [Crossref]