Laser-Synthesis of NV-Centers-Enriched Nanodiamonds - Effect of Different Nitrogen Sources

At a Glance

Metadata	Details
Publication Date	2020-06-09
Journal	Micromachines
Authors	Luca Basso, Mirko Sacco, Nicola Bazzanella, M. Cazzanelli, Alessandro Barge
Institutions	Center for Neuroscience and Cognitive Systems, Italian Institute of Technology
Citations	7
Analysis	Full AI Review Included

Technical Analysis and Documentation: NV-Centers-Enriched Nanodiamonds via Pulsed Laser Ablation

This document analyzes the research paper “Laser-Synthesis of NV-Centers-Enriched Nanodiamonds: Effect of Different Nitrogen Sources” and outlines how 6CCVD’s advanced MPCVD diamond materials and customization capabilities can support and extend this critical research in quantum sensing and nanodiamond synthesis.

Executive Summary

Core Achievement: Successful, single-step synthesis of Nitrogen-Vacancy (NV) centers in nanodiamonds (NDs) using Pulsed Laser Ablation (PLA) of a custom N-doped graphite target.
NV Confirmation: Optically Detected Magnetic Resonance (ODMR) spectroscopy unequivocally confirmed the NV^- origin of the observed photoluminescence (PL) emission.
Efficiency Optimization: Ablation performed in Liquid Nitrogen (LN₂) yielded the highest NV-fluorescence intensity, showing an efficiency 22 ± 4 times greater than the non-irradiated target.
Mechanism Insight: The superior efficiency in LN₂ is attributed to enhanced thermodynamic conditions (high pressure, rapid quenching) within the ablation plume, favoring diamond phase formation.
Tunable Doping: The study demonstrated that varying the initial nitrogen doping level of the graphite target allows for precise control and tuning of the resulting NV center concentration in the NDs.
Application Relevance: The resulting NV-enriched NDs are highly relevant for emerging quantum technologies, including nanoscale magnetic field sensing, temperature sensing, and quantum information protocols.

Technical Specifications

The following hard data points were extracted from the experimental methodology and results:

Parameter	Value	Unit	Context
Laser Wavelength (λ)	248	nm	KrF Excimer Laser source
Pulse Duration (τ)	20	ns	Used for Pulsed Laser Ablation (PLA)
Repetition Rate	10	Hz	Laser operation frequency
Single-Pulse Energy	~500	mJ	Energy delivered to the target surface
High N Target Concentration	23.2	mg/g	Nitrogen concentration in N-doped graphite
Low N Target Concentration	5.8	mg/g	Nitrogen concentration in N-doped graphite
Nanodiamond Size	<100	nm	Clustered nanoparticles (SEM analysis)
ODMR Frequency Shift	~2870	MHz	Characteristic decrease in PL emission proving NV^- centers
PL Intensity Ratio (LN₂/Target)	22 ± 4	Ratio	Highest NV-synthesis efficiency achieved
Substrate Deposition Temp.	~100	°C	Silicon substrate temperature during deposition
Post-Deposition Annealing	300	°C	Used to reduce internal film stresses

Key Methodologies

The synthesis and characterization relied on precise control over precursor preparation, laser parameters, and environmental conditions:

N-Doped Graphite Target Preparation: Graphite powder (7-10 µm) was functionalized using 1,3-dipolar cycloaddition (via glycine/histidine) to incorporate nitrogen atoms onto the sp² carbon surface.
Target Pellet Formation: 200 mg of the N-doped powder was pressed at 50 bar to create a solid target pellet (1 cm diameter, 1 mm thickness).
Pulsed Laser Ablation (PLA) Setup: A KrF excimer laser (λ = 248 nm, τ = 20 ns) was focused onto the target surface (~1 mm² spot size) for 3000 total pulses.
Confining Media Comparison: Ablation was systematically performed in three distinct media to compare NV production efficiency:
- Water (liquid phase).
- Nitrogen atmosphere (1 Pa residual pressure).
- Liquid Nitrogen (LN₂), contained in a polystyrene box to limit evaporation.
Deposition and Post-Processing: Ablated material was deposited onto silicon substrates held at ~100 °C, followed by a 1-hour annealing step at 300 °C to reduce internal stresses.
Characterization: Nitrogen content was quantified via Thermogravimetric Analysis (TGA). Structural (Raman, SEM) and optical properties (PL, ODMR) were used to confirm diamond phase formation and the presence of NV centers.

6CCVD Solutions & Capabilities

The research highlights the critical need for high-quality diamond materials and precise fabrication techniques for quantum applications. While this paper focuses on nanodiamond synthesis, 6CCVD provides the foundational, high-purity bulk materials necessary to replicate, extend, and implement advanced NV-center quantum sensing systems.

Applicable Materials	6CCVD Material Recommendation	Value Proposition for Quantum Research
High-Purity NV Host	Optical Grade Single Crystal Diamond (SCD)	Essential for high-coherence NV research. Our SCD features ultra-low native nitrogen (< 1 ppb), providing a pristine lattice for controlled NV creation via ion implantation, leading to longer spin coherence times than NDs.
Large-Area Platforms	Polycrystalline Diamond (PCD) Wafers	Available in custom dimensions up to 125 mm. Ideal for large-scale integration of quantum sensors or as high-power optical windows/heat spreaders for the 532 nm excitation lasers used in ODMR setups.
Integrated Electronics	Boron-Doped Diamond (BDD)	Available in SCD and PCD. BDD offers tunable conductivity, enabling the creation of integrated electrodes or thermal elements directly adjacent to the NV sensing region, crucial for complex quantum device architectures.

Customization Potential

The paper utilizes silicon substrates and requires precise microwave delivery for ODMR. 6CCVD offers comprehensive customization services to meet these advanced engineering requirements:

Custom Dimensions and Substrates: We provide SCD and PCD plates/wafers in custom sizes and thicknesses (SCD: 0.1 µm - 500 µm; PCD: 0.1 µm - 500 µm; Substrates up to 10 mm thick).
Advanced Polishing: To minimize surface defects and strain (which the paper notes affects NV coherence), 6CCVD guarantees ultra-smooth surfaces: Ra < 1 nm for SCD and Ra < 5 nm for inch-size PCD.
In-House Metalization: For microwave delivery in ODMR experiments, 6CCVD offers custom metal layer deposition (Au, Pt, Pd, Ti, W, Cu). We can fabricate precise contact pads or microwave strip lines directly onto the diamond surface, optimizing RF coupling efficiency.

Engineering Support

6CCVD’s in-house PhD team specializes in the material science of MPCVD diamond for quantum applications. We can assist researchers in selecting the optimal material grade (e.g., SCD vs. PCD, specific doping levels) and fabrication parameters required for similar NV-Center Quantum Sensing projects, ensuring the highest performance and yield.

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

View Original Abstract

Due to the large number of possible applications in quantum technology fields—especially regarding quantum sensing—of nitrogen-vacancy (NV) centers in nanodiamonds (NDs), research on a cheap, scalable and effective NDs synthesis technique has acquired an increasing interest. Standard production methods, such as detonation and grinding, require multistep post-synthesis processes and do not allow precise control in the size and fluorescence intensity of NDs. For this reason, a different approach consisting of pulsed laser ablation of carbon precursors has recently been proposed. In this work, we demonstrate the synthesis of NV-fluorescent NDs through pulsed laser ablation of an N-doped graphite target. The obtained NDs are fully characterized in the morphological and optical properties, in particular with optically detected magnetic resonance spectroscopy to unequivocally prove the NV origin of the NDs photoluminescence. Moreover, to compare the different fluorescent NDs laser-ablation-based synthesis techniques recently developed, we report an analysis of the effect of the medium in which laser ablation of graphite is performed. Along with it, thermodynamic aspects of the physical processes occurring during laser irradiation are analyzed. Finally, we show that the use of properly N-doped graphite as a target for laser ablation can lead to precise control in the number of NV centers in the produced NDs.

Tech Support

Original Source

DOI: https://doi.org/10.3390/mi11060579

References

2019 - Individual control and readout of qubits in a sub-diffraction volume [Crossref]
2019 - Quantum teleportation-based state transfer of photon polarization into a carbon spin in diamond [Crossref]
2008 - High-sensitivity diamond magnetometer with nanoscale resolution [Crossref]
2014 - Magnetometry with nitrogen-vacancy defects in diamond [Crossref]
2013 - Diamond NV centers for quantum computing and quantum networks [Crossref]
2013 - Optical magnetic imaging of living cells [Crossref]
2018 - Probing condensed matter physics with magnetometry based on nitrogen-vacancy centres in diamond [Crossref]
2010 - Quantum register based on coupled electron spins in a room-temperature solid [Crossref]
2013 - Spin relaxometry of single nitrogen-vacancy defects in diamond nanocrystals for magnetic noise sensing [Crossref]
2011 - Electric-field sensing using single diamond spins [Crossref]