Vector Electrometry in a Wide-Gap-Semiconductor Device Using a Spin-Ensemble Quantum Sensor
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2020-10-27 |
| Journal | Physical Review Applied |
| Authors | Bang Yang, Takuya Murooka, KOSUKE MIZUNO, Kwang-soo Kim, Hiromitsu Kato |
| Institutions | Tokyo Institute of Technology, Japan Advanced Institute of Science and Technology |
| Citations | 27 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive SummaryâThis research demonstrates a novel vector electrometry technique utilizing ensemble Nitrogen-Vacancy (NV) centers embedded within a diamond semiconductor device.
- Core Achievement: Successful measurement and resolution of the internal electric field components (Ex and Ez) within a vertical diamond p-i-n diode under high reverse bias (400 V).
- Methodological Advance: The technique overcomes the low sensitivity of axial electrometry by applying a transverse magnetic field (Bperp) to the target NV axis, isolating its ODMR signal from other alignments.
- Sensitivity Enhancement: The use of a transverse magnetic field significantly enhanced the ODMR splitting response to the electric field, achieving an increase in sensitivity by a factor of up to 10 compared to traditional axial magnetic field methods in the measured field range (0.2 to 1.9 MV/cm).
- Device Validation: The measured electric field values (Ex = 0.58 MV/cm, Ez = 1.35 MV/cm at the n+-edge) were found to be in good agreement with device simulations, particularly those models incorporating the effects of implanted Nitrogen donors.
- Spatial Resolution: The study revealed that the Ex component is largely generated in the i-layer, while the Ez component is dominant at the n+-i interface, providing critical insight into device operation.
- Platform: The sensor is integrated directly into a wide-bandgap diamond p-i-n diode, a promising candidate for next-generation low-loss power electronics.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Device Type | Vertical p-i-n diode | N/A | Diamond semiconductor device |
| Substrate Doping ([B]) | 1 x 1017 | cm-3 | Boron-doped (111) diamond substrate |
| n+-Region Doping ([P]) | 1 x 1019 | cm-3 | Heavily phosphorus-doped |
| Intrinsic Layer Thickness | 5 | ”m | i-layer thickness |
| N Ion Implantation Dose | 1 x 1012 | cm-2 | NV center fabrication |
| N Ion Implantation Energy | 350 | keV | NV center fabrication |
| Projected NV Depth | ~350 | nm | From surface, at n+-i interface |
| Maximum Applied Voltage | 400 | V | Reverse bias for E-field generation |
| Rectification Ratio | ~106 | N/A | Measured at ±10 V bias |
| Transverse E Susceptibility (kperp) | 17 | Hz/V/cm | NV center property |
| Gyromagnetic Ratio (Îł) | 28 | GHz/T | NV center property |
| Maximum Measured Ex | 0.58 ± 0.13 | MV/cm | At x=0 ”m, i-layer |
| Maximum Measured Ez | 1.35 ± 0.26 | MV/cm | At x=0 ”m, i-layer |
| Transverse Magnetic Field (NV A target) | 2.1 | mT | Used for signal isolation |
| Transverse Magnetic Field (NV B target) | 4.1 | mT | Used for signal isolation |
| Measurement Vacuum | ~6 x 10-3 | Pa | To prevent high-voltage discharge |
| Annealing Temperature | 750 | °C | Post-implantation NV formation |
Key Methodologies
Section titled âKey MethodologiesâThe vector electrometry was achieved through precise device fabrication, targeted NV center alignment selection, and ODMR spectroscopy under controlled magnetic and electric fields.
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Device Fabrication and NV Formation:
- A vertical p-i-n diode was constructed on a (111) diamond substrate.
- NV centers were created via Nitrogen ion implantation (350 keV, 1x1012 cm-2 dose) at 600°C, followed by annealing at 750°C for 30 minutes.
- This process placed ensemble NV centers approximately 350 nm deep, near the n+-i interface.
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Transverse Magnetic Field Application:
- Three-axis electromagnets were used to apply a magnetic field (B) in the lab frame.
- A transverse magnetic field (Bperp) was specifically applied perpendicular to the axis of the target NV alignment (e.g., NV A).
- This Bperp field minimizes the ODMR splitting of the target NV axis while maximizing the splitting of the non-target axes, allowing the target signal to be isolated near the zero-field splitting (Dgs).
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Electric Field Measurement and Enhancement:
- A high reverse voltage (400 V) was applied to the p-i-n diode in a vacuum environment (~6x10-3 Pa).
- The electric field (Eperp) transverse to the target NV axis caused a measurable shift and splitting (W) in the ODMR resonance frequency.
- The use of Bperp ensured that the splitting width (W) was highly sensitive and increased almost linearly with the effective electric field (Î perp), achieving the factor of 10 enhancement over axial field methods.
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Vector Component Resolution:
- The measurement process (applying Bperp and E) was repeated sequentially for multiple NV alignments (NV A and NV B).
- The effective transverse electric field (ENV iperp) measured for each alignment was used in a system of equations (Equation 2) based on the known crystallographic directions of the NV axes.
- Solving this system yielded the spatial components of the electric field (Ex and Ez) in the lab frame.
Commercial Applications
Section titled âCommercial ApplicationsâThis vector electrometry technique is highly relevant for industries requiring high-resolution, non-invasive internal field mapping in solid-state devices.
- High-Power Semiconductor Technology:
- Device Optimization: Essential for characterizing and optimizing wide-bandgap devices (like diamond, SiC, and GaN power diodes) where high internal electric fields (MV/cm range) are sustained.
- Reliability Engineering: Identifying localized field concentrations that lead to premature breakdown or failure in high-voltage power electronics.
- Quantum Device Integration and Control:
- Quantum Sensing Platforms: Diamond devices are used as platforms for quantum technologies. Mapping the internal electric field is crucial for understanding and controlling the quantum states of embedded defects (like NV centers) for sensing or computation.
- Strain Mapping: The technique inherently measures the combined effect of electric field and strain (Î perp = Eperp + Ïperp). Further refinement can lead to high-resolution strain mapping in microelectronic structures.
- Micro- and Nano-Electronics:
- IC Diagnostics: Non-invasive probing of electric fields within operating integrated circuits, offering insights into charge trapping, leakage paths, and device physics that surface probes cannot access.
- Materials Science and Defect Engineering:
- Process Validation: Directly validating the impact of doping profiles and implantation processes on the resulting internal fields, aiding in the development of advanced semiconductor fabrication recipes.
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.