High Sensitivity Spin Defects in Carbon Implanted Diamond

At a Glance

Metadata	Details
Publication Date	2025-04-21
Journal	Advanced Optical Materials
Authors	X.D. Chai, Haidong Liang, Chengyuan Yang, Vinh X. Ho, Ee Jin Teo
Institutions	National University of Singapore, Australian Nuclear Science and Technology Organisation
Analysis	Full AI Review Included

High Sensitivity Spin Defects in Carbon Implanted Diamond: Technical Analysis and 6CCVD Solutions

This document analyzes the research paper “High Sensitivity Spin Defects in Carbon Implanted Diamond” and outlines how 6CCVD’s advanced MPCVD diamond materials and customization capabilities can support the replication, optimization, and scaling of this critical quantum sensing technology.

Executive Summary

The research successfully validates the TR12 color center as a highly promising alternative to the Nitrogen-Vacancy (NV) center for room-temperature vector magnetometry.

Record Sensitivity Achieved: A shot-noise-limited magnetic sensitivity of 1.2 nT/√Hz was achieved, representing a three-order-of-magnitude improvement over previous TR12 literature and surpassing many SiC and hBN spin defects.
Material and Method: Optimization was performed using high-energy (25 MeV) Carbon (C+) ion microbeam line-scan irradiation on E-grade Type IIa HPHT synthetic diamond plates.
Spatial Optimization: Cross-sectional 2D photoluminescence (PL) imaging was critical for spatially mapping TR12 emitter density and optimizing ODMR contrast and linewidth along the ion cascade depth.
Coherence Demonstrated: Coherent spin manipulation was confirmed via Rabi oscillation measurements, yielding Rabi decoherence times (T_Rabi) of approximately 0.42 µs at the end-of-range (EOR).
Vector Magnetometry Potential: The high ODMR contrast and wide acceptance angles of TR12 confirm its prospective use for vector magnetometry, overcoming limitations faced by NV centers in strong off-axis magnetic fields.
Material Requirement: The study highlights the necessity of high-purity, low-defect diamond substrates for controlled defect engineering and maximizing ensemble coherence.

Technical Specifications

The following hard data points were extracted from the research paper, detailing the experimental parameters and key performance metrics of the optimized TR12 ensemble.

Parameter	Value	Unit	Context
Achieved Magnetic Sensitivity (Optimal)	1.2	nT/√Hz	Shot-noise-limited sensitivity (Highest Fluence, Location 1)
Sensitivity Improvement	3	Orders of Magnitude	Improvement over prior TR12 literature
Diamond Material Used	E-grade Type IIa HPHT	N/A	High-purity synthetic diamond substrate
Substrate Dimensions	4 x 4 x 0.5	mm³	Plate size used for irradiation
Irradiation Species & Energy	25	MeV C+	High-energy carbon ion microbeam
Optimal Irradiation Fluence	5 x 10¹⁴	ions cm^-2	Fluence yielding the highest emitter density and count rates
TR12 Zero-Phonon Line (ZPL)	470.2	nm	Characteristic emission wavelength
ODMR Signal Frequency	740	MHz	Frequency used for spin manipulation
Maximum ODMR Contrast	22.2	%	Observed at 1 x 10¹⁴ ions cm^-2, Location 1
Minimum ODMR Linewidth (Δν)	4.28	MHz	Observed at 1 x 10¹⁴ ions cm^-2, Location 3
Rabi Decoherence Time (T_Rabi)	≈0.42 to ≈0.47	µs	As-implanted, measured near surface and end-of-range (EOR)
Annealing Conditions	460 °C for 3h	Vacuum	Post-irradiation treatment

Key Methodologies

The experiment relied on precise material selection, high-energy ion implantation, and advanced optical characterization techniques to optimize the TR12 defect ensembles.

Substrate Selection: Use of a high-purity E-grade Type IIa HPHT synthetic diamond plate (4 x 4 x 0.5 mm³), polished on all surfaces to minimize native defects and maximize optical clarity.
Focused Ion Microbeam Irradiation: Precision line-scan irradiation performed using a 25 MeV Carbon (C+) ion microbeam, extending across the plate edge to enable cross-sectional analysis of the ion cascade.
Fluence Tuning: Three specific irradiation fluences were tested (1 x 10¹⁴, 3 x 10¹⁴, and 5 x 10¹⁴ ions cm^-2) to control the local defect distribution and aggregation along the ion track.
Cross-Sectional PL Mapping: Confocal microscopy with a 405 nm excitation laser was used to map the spatial distribution and intensity of TR12 (470.2 nm ZPL) and competing defects (3H, GR1) along the depth profile of the ion cascade.
ODMR Optimization: Optically Detected Magnetic Resonance (ODMR) measurements were performed at 740 MHz, systematically varying laser power (up to 13 mW) and microwave power to optimize the critical parameters: contrast (C_cw) and linewidth (Δν).
Coherent Spin Manipulation: Rabi oscillation measurements were conducted under a weak magnetic field, and the resulting damped oscillations were fitted to determine the Rabi frequency (Ω_R) and decoherence time (T_Rabi).
Post-Processing Analysis: The effect of post-irradiation annealing (460 °C in vacuum) on T_Rabi was investigated, although it was found not to be strictly necessary for achieving optimal decoherence times.

6CCVD Solutions & Capabilities

6CCVD specializes in providing the high-quality, customizable MPCVD diamond substrates essential for replicating and advancing this cutting-edge quantum sensing research. Our capabilities directly address the material and fabrication requirements demonstrated in the TR12 optimization study.

Applicable Materials

To replicate or extend this research, a substrate with minimal native defects and high crystalline quality is paramount for maximizing the coherence time of the implanted TR12 ensembles.

Research Requirement	6CCVD Material Recommendation	Technical Rationale
High Purity Substrate (E-grade Type IIa)	Optical Grade Single Crystal Diamond (SCD)	Our SCD material offers ultra-low nitrogen content (< 1 ppb), minimizing background NV centers and other paramagnetic impurities that interfere with TR12 coherence and ODMR contrast.
High Defect Density Tolerance	Polycrystalline Diamond (PCD) or SCD	For scaling up ensemble sensing, our high-quality PCD wafers (up to 125mm) offer a cost-effective platform for large-area, high-fluence ion implantation studies.
Future Sensing Integration	Boron-Doped Diamond (BDD)	For integration with electrochemistry or high-current applications, we offer BDD films, which can be engineered for specific conductivity requirements while maintaining optical quality.

Customization Potential

The success of the TR12 study relied on precise dimensions and surface quality. 6CCVD offers full customization to meet exact experimental needs.

Custom Dimensions and Thickness: While the paper used 4 x 4 x 0.5 mm³ plates, 6CCVD provides SCD plates with custom dimensions and thicknesses ranging from 0.1 µm to 500 µm for active layers, and robust substrates up to 10 mm thick. We support large-area research with PCD wafers up to 125 mm in diameter.
Ultra-Precision Polishing: The study requires excellent surface quality for confocal microscopy. We guarantee Ra < 1 nm polishing for SCD, ensuring minimal scattering and optimal optical access for high-NA objectives.
Integrated Metalization: The ODMR setup requires a microwave chip/waveguide. 6CCVD offers in-house metalization services (including Au, Pt, Pd, Ti, W, and Cu) for direct integration of RF structures onto the diamond surface, streamlining device fabrication.
Global Supply Chain: We ensure reliable, global shipping (DDU default, DDP available) of sensitive diamond materials to research facilities worldwide.

Engineering Support

The optimization of TR12 defects is complex, involving the interplay of interstitial carbon atoms, vacancy concentrations, and specific fluence levels.

Defect Engineering Consultation: 6CCVD’s in-house PhD team specializes in material science and defect physics. We offer consultation to assist researchers in selecting the optimal diamond orientation, purity, and thickness required for specific ion implantation parameters (energy, species, fluence) to maximize TR12 formation and coherence for vector magnetometry projects.
Material Characterization: We provide detailed material characterization data, ensuring the starting substrate quality meets the stringent requirements necessary to replicate the high-sensitivity results achieved in this paper.

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

View Original Abstract

Abstract The TR12 color center in diamond is a self‐interstitial spin defect capable of room‐temperature atomic‐scale vector magnetometry for detecting magnetic fields of arbitrary orientation and magnitude. Measurements using the TR12 center show that the sensing dynamic range can potentially outperform that of NV centers in diamond. The powerful quantum sensing capabilities of TR12 place it as a strong alternative candidate for quantum sensing in diamond, especially in extreme magnetic fields. However, its sensitivity in existing literature is relatively low in the µT/√Hz range. This work examines the spatial distributions of TR12 centers fabricated by high‐energy carbon irradiation on an E‐grade diamond along the ion irradiation cascade. A detailed study of photoluminescence intensity, optically detected magnetic resonance contrast, and linewidth is conducted. By varying locations along ion cascades of line irradiations with different fluences, the highest sensitivity of 1.2 nT/√Hz is achieved at three orders of magnitude higher than demonstrated in existing literatures. Coherent manipulation of triplet spin states in these ensembles is evident from Rabi oscillation measurements, with decoherence times of ≈0.47 µs at the surface and ≈ 0.42 µs at the end‐of‐range. These findings significantly enhance the potential of TR12 for quantum sensing applications.