Vector Electrometry in a Wide-Gap-Semiconductor Device Using a Spin-Ensemble Quantum Sensor

At a Glance

Metadata	Details
Publication Date	2020-10-27
Journal	Physical Review Applied
Authors	Bang Yang, Takuya Murooka, KOSUKE MIZUNO, Kwang-soo Kim, Hiromitsu Kato
Institutions	Harvard University, Japan Advanced Institute of Science and Technology
Citations	27
Analysis	Full AI Review Included

Technical Documentation & Analysis: Vector Electrometry in Diamond Quantum Sensors

This document analyzes the research demonstrating vector electrometry using ensemble Nitrogen-Vacancy (NV) centers embedded in a diamond p-i-n diode. This work highlights the critical role of high-quality, customized MPCVD diamond in advancing integrated quantum sensing and high-power electronics.

Executive Summary

This research successfully demonstrates vector electrometry—the measurement of electric field components (E_x and E_z)—inside a vertical diamond p-i-n diode using ensemble NV centers as quantum sensors.

Core Achievement: Direct measurement of internal electric fields (up to 1.9 MV/cm) within a wide-gap semiconductor device.
Methodological Breakthrough: Utilizing a transverse magnetic field (B_⊥) applied to specific NV alignments, the sensitivity of the ODMR response to the electric field was enhanced by a factor of 10 compared to conventional axial magnetic field methods.
Material Platform: The device was built on a Boron-doped (111) Single Crystal Diamond (SCD) substrate, leveraging diamond’s wide band gap and high thermal conductance for high-voltage operation (400 V reverse bias).
Sensor Integration: Ensemble NV centers were created via Nitrogen ion implantation (1x10¹² cm^-2 dose) and subsequent annealing, positioning the sensors approximately 350 nm from the surface.
Application Relevance: This technique is crucial for optimizing next-generation low-loss diamond power electronics and developing integrated quantum sensing platforms.

Technical Specifications

The following hard data points were extracted from the research paper detailing the device structure and measurement results:

Parameter	Value	Unit	Context
Substrate Orientation	(111)	Crystal Plane	Required for specific NV alignment analysis
Substrate Doping (p-layer)	1x10¹⁷	cm^-3	Boron concentration in SCD substrate
n⁺ Region Doping	1x10¹⁹	cm^-3	Heavily Phosphorus-doped regions
Intrinsic Layer (i-layer) Thickness	5	µm	Thickness of the undoped layer
NV Implantation Dose (N)	1x10¹²	cm^-2	Nitrogen ion dose for ensemble NV creation
NV Projected Depth	~350	nm	Location of the ensemble NV layer
Annealing Temperature	750	°C	Post-implantation thermal treatment
Applied Reverse Voltage	400	V	Voltage used to generate internal E-field
Transverse Magnetic Field (B_⊥)	2.1 and 4.1	mT	Used to target NV A and NV B axes, respectively
Maximum Measured E-Field (E_z)	1.35 ± 0.26	MV/cm	Vertical component at n⁺-i interface
Maximum Measured E-Field (E_x)	0.58 ± 0.13	MV/cm	Transverse component in the i-layer
Rectification Ratio	~10⁶	N/A	Electrical performance of the p-i-n diode at ±10 V

Key Methodologies

The vector electrometry demonstration relied on precise material engineering and specialized quantum measurement techniques:

Substrate Preparation: A vertical p-i-n diode structure was fabricated on a Boron-doped (111) Single Crystal Diamond (SCD) substrate.
Layer Deposition/Doping: A 5 µm intrinsic layer and patterned 350 nm thick heavily Phosphorus-doped (n⁺) regions (1x10¹⁹ cm^-3) were created.
NV Center Creation: Nitrogen ions were implanted over the device at a dose of 1x10¹² cm^-2 with an acceleration energy of 350 keV at 600°C.
Vacancy Diffusion: The device was annealed at 750°C for 30 minutes to promote vacancy diffusion and form ensemble NV centers at a projected depth of ~350 nm.
Measurement Environment: Experiments were conducted at room temperature in a vacuum chamber (~6x10^-3 Pa) to prevent electrical discharge at high voltages.
Quantum Sensing Control: A 532 nm green laser was used for NV excitation, and Microwave (MW) radiation was applied via a thin Cu wire for Optically Detected Magnetic Resonance (ODMR).
Vector Isolation: Three-axis electromagnets were used to apply a transverse magnetic field (B_⊥) to a target NV alignment (e.g., NV A or NV B), isolating its ODMR signal and significantly enhancing the electric field response (up to 10x).
Field Calculation: By repeating the measurement for multiple NV axes (NV A and NV B), the components of the electric field (E_x and E_z) generated by the applied 400 V reverse bias were calculated using a system of equations.

6CCVD Solutions & Capabilities

6CCVD is uniquely positioned to supply the high-specification diamond materials required to replicate, scale, and advance this critical research in integrated quantum sensing and diamond power electronics.

Applicable Materials

To achieve the high-voltage operation and precise NV alignment demonstrated in this paper, researchers require highly controlled, low-strain single crystal diamond.

Research Requirement	6CCVD Solution	Material Specification
Substrate Material	Boron-Doped Diamond (BDD) SCD	High-quality (111) or (100) orientation SCD with precise Boron doping control (e.g., 1x10¹⁷ cm^-3).
Intrinsic Layer	High-Purity Single Crystal Diamond (SCD)	Ultra-low nitrogen concentration (< 1 ppb) SCD for the 5 µm i-layer, ensuring minimal background defects and optimal NV coherence.
NV Precursors	Controlled Nitrogen Doping	SCD wafers with controlled, low-level nitrogen incorporation during growth, optimized for subsequent ion implantation and annealing processes.
Surface Quality	Polished SCD Wafers	SCD polished to Ra < 1 nm, essential for minimizing surface defects that contribute to strain (σ_⊥) and inhomogeneous broadening of ODMR signals.

Customization Potential

The fabrication of the p-i-n diode requires precise material dimensions and integration capabilities, which 6CCVD provides as a standard service:

Custom Dimensions: 6CCVD supplies SCD plates and wafers up to 125 mm in size, allowing for scaling of these integrated quantum devices beyond laboratory prototypes.
Thickness Control: We offer SCD layers from 0.1 µm up to 500 µm, enabling precise control over the 5 µm intrinsic layer thickness critical for device performance and electric field distribution.
Advanced Metalization: The device requires cathode metal electrodes (M) on the n⁺ regions. 6CCVD offers in-house metalization services, including deposition of Au, Pt, Pd, Ti, W, and Cu stacks, tailored for ohmic contacts on doped diamond.
Substrate Engineering: We provide custom substrate thicknesses (up to 10 mm) and precise orientation control, including the specific (111) orientation used in this vector electrometry study.

Engineering Support

The successful implementation of NV electrometry relies heavily on minimizing strain and optimizing the NV creation process.

Strain Management: 6CCVD’s in-house PhD team specializes in providing low-strain SCD materials, which is crucial since the strain field (σ_⊥) contributes significantly to the effective electric field (Π_⊥) measurement error (estimated up to 0.2 MV/cm in the paper).
Material Selection for Quantum Applications: Our experts can assist researchers in selecting the optimal diamond grade (e.g., high-purity SCD vs. PCD) and crystal orientation for specific quantum sensing projects, including magnetometry, thermometry, and high-resolution electrometry.

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

View Original Abstract

Nitrogen-vacancy (N-V) centers in diamond work as a quantum electrometer. Using an ensemble state of N-V centers, we propose vector electrometry and demonstrate measurements in a diamond electronic device. A transverse electric field applied to the N-V axis under a high voltage is measured, while applying a transverse magnetic field. The response of the energy-level shift against the electric field is significantly enhanced compared with that against an axial magnetic field. Repeating the measurement of the transverse electric field for multiple N-V axes, our team obtains the components of the electric field generated in the device.

Tech Support

Original Source

DOI: https://doi.org/10.1103/physrevapplied.14.044049