Room Temperature Electrically Detected Nuclear Spin Coherence of NV Centres in Diamond

At a Glance

Metadata	Details
Publication Date	2020-01-21
Journal	Scientific Reports
Authors	Hiroki Morishita, S. Kobayashi, Masanori Fujiwara, Hiromitsu Kato, Toshiharu Makino
Institutions	Kyoto University Institute for Chemical Research, Kyoto University
Citations	28
Analysis	Full AI Review Included

Technical Analysis and Documentation: Electrically Detected Nuclear Spin Coherence in Diamond

This document analyzes the research demonstrating room-temperature electrical detection of ¹⁴N nuclear spin coherence in Nitrogen-Vacancy (NV) centers in diamond, and maps the material requirements to 6CCVD’s advanced MPCVD diamond capabilities.

Executive Summary

The research successfully demonstrates the electrical detection of nuclear spin coherence (T₂⁽ⁿ⁾) in NV centers at room temperature using Electrically Detected Electron-Nuclear Double Resonance (EDENDOR). This breakthrough is critical for developing scalable, integrated diamond quantum devices.

Core Achievement: First demonstration of room-temperature electrical detection of ¹⁴N nuclear spin coherence (Rabi oscillations and T₂⁽ⁿ⁾) in diamond.
Quantum Memory Potential: Observed T₂⁽ⁿ⁾ ≈ 0.9 ms at 300 K, confirming the viability of NV nuclear spins as long-lived quantum memories.
Material Requirement: The experiment relies on a highly controlled, 10 µm thick, P-doped n-type Single Crystal Diamond (SCD) layer grown on a Type IIa (001) substrate.
Detection Sensitivity: Electrical detection (EDENDOR) is theoretically three times more sensitive than traditional optical techniques, facilitating the integration of quantum sensors and memories into semiconductor architectures.
6CCVD Value Proposition: 6CCVD provides the necessary high-purity (001) SCD substrates, custom doping expertise (e.g., BDD, demonstrating precise control), and critical in-house metalization (Ti/Pt/Au) required for replicating and scaling this advanced quantum research.

Technical Specifications

Parameter	Value	Unit	Context
Nuclear Spin Coherence Time (T₂⁽ⁿ⁾)	0.9 (±0.5)	ms	Observed at Room Temperature (Lower Limit)
Electron Spin Relaxation Time (T₁^(e))	1.8 (±0.6)	ms	Measured via EDMR technique
P-Donor Concentration	~10¹⁸	cm^-3	Required for high electrical conductivity in the n-type layer
¹⁴N⁺ Ion Implantation Dose	1 x 10¹⁵	cm^-2	Used to create NV centers
Diamond Layer Thickness	10	µm	P-doped n-type layer grown by CVD
Substrate Orientation	(001)	N/A	Type IIa SCD substrate used for epitaxial growth
Operating Temperature	Room Temperature	K	300 K operation demonstrated
Applied DC Voltage	8	V	Constant voltage for photocurrent measurement
Laser Wavelength	532	nm	Used for initialization and two-photon ionization
MW Resonance Frequency	2916	MHz	Corresponds to the
Nuclear Resonance Frequency	3.5	MHz	Observed ¹⁴N ENDOR signal
Contact Metal Stack	Ti/Pt/Au	N/A	Ti(30 nm)/Pt(30 nm)/Au(100 nm) multi-layers

Key Methodologies

The successful demonstration relies on precise material engineering and advanced device fabrication steps:

Substrate Selection: Use of high-quality Type IIa (001) Single Crystal Diamond (SCD) substrates.
CVD Growth: Synthesis of a 10 µm thick P-doped n-type diamond layer via Chemical Vapor Deposition (CVD).
Controlled Doping: Achieving a P-donor concentration of ~10¹⁸ cm^-3 to ensure high electrical conductivity.
NV Center Generation: Creation of NV centers via ¹⁴N⁺-ion implantation (Dose: 1 x 10¹⁵ cm^-2, 350 keV).
Post-Implantation Processing: High-temperature annealing at 1000 °C for 1 hour under vacuum.
Contact Definition: Electron-beam lithography used to define interdigital contacts with ~2 µm gaps.
Metalization Stack Deposition: Sequential deposition of Ti(30 nm)/Pt(30 nm)/Au(100 nm) multi-layers.
Ohmic Contact Formation: Annealing the metal contacts at 420 °C for 30 minutes under Argon atmosphere.
Measurement: Utilizing a self-built EDENDOR spectrometer combining 532 nm laser illumination, MW/RF irradiation, and photocurrent detection under an 8 V bias.

6CCVD Solutions & Capabilities

6CCVD is uniquely positioned to supply the high-specification MPCVD diamond materials and custom fabrication services required to replicate and advance this research into scalable quantum devices.

Applicable Materials

The research requires highly controlled, low-strain diamond material with specific doping and orientation.

Material Requirement	6CCVD Material Solution	Technical Advantage
Substrate Base	Optical Grade SCD (001 Orientation)	Provides the necessary high-purity, low-defect foundation for epitaxial growth and subsequent ion implantation.
Doping Control	Custom Doped SCD	While the paper used P-doping, 6CCVD’s expertise in controlled doping (e.g., heavy Boron-Doped Diamond, BDD) confirms our capability to manage dopant incorporation for n-type or p-type layers required for integrated devices.
Active Layer Thickness	SCD (0.1 µm to 500 µm)	We can precisely grow or supply the required 10 µm thick active layer with excellent uniformity, critical for consistent device performance.

Customization Potential

The device fabrication process demands precise control over geometry, surface finish, and metal contacts—all core 6CCVD capabilities.

Research Requirement	6CCVD Customization Service	Benefit to Researcher
Metal Contacts	In-House Custom Metalization	We offer internal deposition of the exact Ti/Pt/Au stack (or other combinations like Pd, W, Cu) required for ohmic contacts, delivering ready-to-pattern wafers.
Surface Finish	Ultra-Low Roughness Polishing	Our SCD polishing achieves Ra < 1 nm, which is essential for high-fidelity electron-beam lithography used to define the critical 2 µm interdigital gaps.
Scaling & Integration	Custom Dimensions (up to 125 mm PCD)	For future integration, 6CCVD can provide large-area PCD or SCD plates, enabling the transition from small research samples to wafer-scale quantum circuit fabrication.
Substrate Thickness	Custom Substrates (up to 10 mm)	We supply robust, thick substrates necessary for handling and integration into complex experimental setups.

Engineering Support

The successful electrical detection of nuclear spin coherence opens new avenues for integrated quantum sensing and memory applications.

Application Focus: 6CCVD’s in-house PhD team specializes in material selection and optimization for advanced quantum applications, including NV center physics, quantum memory, and high-sensitivity magnetic sensing.
Material Consultation: We offer expert guidance on optimizing CVD growth parameters, substrate orientation, and surface termination to maximize T₂ coherence times and enhance electrical conductivity for similar Electron- and Nuclear-Spin-Based Diamond Quantum Devices projects.
Global Logistics: We ensure reliable, global shipping (DDU default, DDP available) of sensitive, high-value diamond materials directly to your lab.

Call to Action: For custom specifications, material consultation, or to discuss your next quantum diamond project, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

Abstract We demonstrate electrical detection of the 14 N nuclear spin coherence of NV centres at room temperature. Nuclear spins are candidates for quantum memories in quantum-information devices and quantum sensors, and hence the electrical detection of nuclear spin coherence is essential to develop and integrate such quantum devices. In the present study, we used a pulsed electrically detected electron-nuclear double resonance technique to measure the Rabi oscillations and coherence time ( T 2 ) of 14 N nuclear spins in NV centres at room temperature. We observed T 2 ≈ 0.9 ms at room temperature, however, this result should be taken as a lower limit due to limitations in the longitudinal relaxation time of the NV electron spins. Our results will pave the way for the development of novel electron- and nuclear-spin-based diamond quantum devices.

Tech Support

Original Source

DOI: https://doi.org/10.1038/s41598-020-57569-8