Integration of Fluorescent, NV-Rich Nanodiamond Particles with AFM Cantilevers by Focused Ion Beam for Hybrid Optical and Micromechanical Devices

At a Glance

Metadata	Details
Publication Date	2021-10-29
Journal	Coatings
Authors	Mateusz Ficek, Maciej J. Głowacki, Krzysztof Gajewski, Piotr Kunicki, Ewelina Gacka
Institutions	Gdańsk University of Technology, Wrocław University of Science and Technology
Citations	8
Analysis	Full AI Review Included

Technical Documentation & Analysis: NV-Rich Diamond AFM Probes

Reference Paper: Ficek et al., “Integration of Fluorescent, NV-Rich Nanodiamond Particles with AFM Cantilevers by Focused Ion Beam for Hybrid Optical and Micromechanical Devices,” Coatings 2021, 11, 1332.

Executive Summary

This research successfully demonstrates a novel fabrication technique for creating hybrid Atomic Force Microscopy (AFM) probes integrating Nitrogen-Vacancy (NV)-rich nanodiamond particles, enabling high-resolution scanning magnetometry via Optically Detected Magnetic Resonance (ODMR).

Hybrid Device Achievement: Successful integration of NV-rich nanodiamonds onto standard AFM cantilever tips using Focused Ion Beam (FIB) milling and Focused Electron Beam-Induced Deposition (FEBID).
Enhanced Resolution & Durability: The diamond-tipped probe achieved superior imaging quality on Highly Oriented Pyrolytic Graphite (HOPG), yielding a lower Root Mean Square (RMS) roughness (2.23 nm) compared to the standard platinum-coated tip (3.47 nm), confirming the high abrasion resistance of the diamond material.
Nanoparticle Preparation: Ultrasonic disintegration was employed to precisely control the size and shape of commercial NV-rich nanodiamonds, targeting particles < 500 nm with sharp edges for optimal tip geometry.
ODMR Functionality: The fabricated probes successfully generated ODMR signals, demonstrating their potential for enhanced magnetometric sensitivity and nanometric resolution in scanning probe applications.
Critical Challenge Identified: Significant tip heating (estimated at ~300 °C) was observed due to the excitation laser power (50 mW), highlighting the critical need for diamond materials with superior thermal management properties.
6CCVD Value Proposition: 6CCVD provides the high-purity, high-thermal-conductivity Single Crystal Diamond (SCD) required to mitigate thermal drift and maximize NV center coherence time for next-generation quantum sensing probes.

Technical Specifications

Parameter	Value	Unit	Context
Initial Nanodiamond Size	~1	µm	Average particle size (commercial source)
Target Nanodiamond Size	< 500	nm	Required for optimal tip geometry
Target Nanodiamond Height	< 0.5	µm	Maximum height for mounting slot
NV Center Concentration	Up to 3	ppm	In commercial nanodiamonds used
FIB Milling Voltage	30	kV	Gallium ion source for slot preparation
FEBID Electron Beam Voltage	2	kV	Used for Pt(C) deposition (fixing particle)
Excitation Laser Wavelength	532	nm	Green laser (Sprout-H)
ODMR Frequency	2.87	GHz	Microwave signal frequency
Maximum ODMR Contrast (0 Field)	0.7	%	Observed in bulk diamond mono-crystals
RMS Roughness (Standard Tip)	3.47	nm	PPP-ContPt AFM probe on HOPG
RMS Roughness (NV-Rich Tip)	2.23	nm	Diamond-tipped probe on HOPG
Estimated Tip Heating	~300	°C	Due to 50 mW laser power
AFM Tip Resonant Frequency Shift	+8 to -57	Hz	Observed variation after 1 hour of scanning

Key Methodologies

The fabrication of the hybrid AFM/NV-rich nanodiamond probe involved precise material preparation and advanced nanomanipulation techniques:

Nanodiamond Preparation: Commercial NV-rich nanodiamond particles (1 µm average size, up to 3 ppm NV centers) were suspended in isopropyl alcohol (IPA).
Size Reduction: Ultrasonic disintegration (5 to 60 min active operation) was applied to fragment the particles, aiming for a size distribution centered around 500 nm or less with sharp, tip-like geometry.
FIB Milling (Step 2): A slot was prepared on the apex of a standard platinum-coated AFM cantilever tip using a 30 kV Gallium ion Focused Ion Beam (FIB) source.
Nanomanipulation (Step 3): A suitable NV-rich nanodiamond particle (< 500 nm, < 0.5 µm height) was selected from a silicon substrate using a nano-manipulator, relying on adhesive forces for transfer.
FEBID Integration (Step 3): The particle was fixed into the FIB-milled slot on the AFM tip using Focused Electron Beam-Induced Deposition (FEBID) of Platinum-Carbon (Pt(C)) material, utilizing a 2 kV electron beam.
Testing: The final probes were tested for imaging performance (RMS roughness on HOPG) and quantum sensing capability (fluorescence spectroscopy and ODMR measurements).

6CCVD Solutions & Capabilities

The successful replication and advancement of this high-resolution scanning magnetometry technique rely heavily on the quality, purity, and customizability of the diamond material. 6CCVD is uniquely positioned to supply the necessary MPCVD diamond substrates and engineered components.

Applicable Materials for Quantum Sensing

The paper highlights the need for durable, high-quality diamond material to ensure superior imaging and stable NV center performance.

6CCVD Material Recommendation	Rationale & Advantage
Optical Grade Single Crystal Diamond (SCD)	Thermal Management: SCD offers the highest thermal conductivity (up to 2200 W/mK), essential for dissipating the heat generated by the 532 nm excitation laser (which caused ~300 °C heating in the experiment). Mitigating thermal drift is critical for stable ODMR and long coherence times.
High Purity SCD Substrates	NV Center Quality: Provides a superior, low-defect starting material for precise creation of NV centers (via implantation or subsequent growth), ensuring higher contrast and longer spin coherence times (T₂) than commercial nanodiamonds.
Polycrystalline Diamond (PCD) Wafers	Large Area Precursors: For high-throughput fabrication of multiple tips or large-scale nanodiamond production, 6CCVD offers PCD wafers up to 125 mm in diameter, providing consistent material quality.
Custom Boron-Doped Diamond (BDD)	Integrated Conductivity: If electrical contact or integrated microwave delivery is required, BDD can be engineered to provide conductive pathways directly within the diamond structure, enhancing device functionality.

Customization Potential for Hybrid Probes

6CCVD’s in-house engineering capabilities directly address the precise dimensional and integration requirements demonstrated in this research.

Precision Diamond Machining: The experiment required nanodiamond particles < 500 nm with sharp, tip-like geometry. 6CCVD offers custom laser cutting and etching services to produce SCD or PCD structures with precise dimensions (down to 0.1 µm thickness) and high aspect ratios, ensuring optimal tip radius for atomic-scale resolution.
Advanced Metalization Services: While the paper used Pt(C) FEBID for fixing, 6CCVD offers standard and custom metalization stacks (Au, Pt, Pd, Ti, W, Cu) for creating integrated contact pads, microwave striplines, or reflective layers to enhance photon collection efficiency, directly addressing the challenges mentioned in the literature review (Choi et al. [20]).
Thickness Control: We can supply SCD or PCD layers with thickness control from 0.1 µm up to 500 µm, allowing researchers to optimize the volume of NV-rich material for high-density sensing ensembles, balancing sensitivity and spatial resolution.
Polishing Excellence: Our SCD polishing capability achieves surface roughness Ra < 1 nm, ensuring the highest quality interface for subsequent FIB/FEBID integration and minimizing scattering losses for optical readout.

Engineering Support

6CCVD’s in-house PhD team specializes in MPCVD growth parameters and material science for quantum applications. We can assist researchers in selecting the optimal diamond material (purity, doping, orientation) and geometry required for similar Scanning NV Magnetometry projects, ensuring maximum NV center performance and thermal stability.

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

View Original Abstract

In this paper, a novel fabrication technology of atomic force microscopy (AFM) probes integrating cantilever tips with an NV-rich diamond particle is presented. Nanomanipulation techniques combined with the focused electron beam-induced deposition (FEBID) procedure were applied to position the NV-rich diamond particle on an AFM cantilever tip. Ultrasonic treatment of nanodiamond suspension was applied to reduce the size of diamond particles for proper geometry and symmetry. The fabricated AFM probes were tested utilizing measurements of the electrical resistance at highly oriented pyrolytic graphite (HOPG) and compared with a standard AFM cantilever performance. The results showed novel perspectives arising from combining the functionalities of a scanning AFM with optically detected magnetic resonance (ODMR). In particular, it offers enhanced magnetometric sensitivity and the nanometric resolution.

Tech Support

Original Source

DOI: https://doi.org/10.3390/coatings11111332

References

2013 - Nanoscale magnetometry with NV centers in diamond [Crossref]
2016 - Fabrication of All Diamond Scanning Probes for Nanoscale Magnetometry [Crossref]
2008 - Scanning magnetic field microscope with a diamond single-spin sensor [Crossref]
2008 - High-sensitivity diamond magnetometer with nanoscale resolution [Crossref]
2008 - Nanoscale magnetic sensing with an individual electronic spin in diamond [Crossref]
2012 - Nanoscale magnetic field mapping with a single spin scanning probe magnetometer [Crossref]
2013 - Stray-field imaging of magnetic vortices with a single diamond spin [Crossref]
1990 - Tip-Related Artifacts in Scanning Tunneling Potentiometry [Crossref]
1993 - Tip Artifacts in Atomic Force Microscope Imaging of Thin Film Surfaces [Crossref]
1998 - Characterization of Atomic Force Microscopy (AFM) Tip Shapes by Scanning Hydrothermally Deposited ZnO Thin Films [Crossref]