Формирование многослойных наноструктур NV-центров в монокристаллическом CVD-алмазе
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2020-01-01 |
| Journal | Письма в журнал технической физики |
| Authors | А.М. Горбачев, М.А. Лобаев, Д.Б. Радищев, А.Л. Вихарев, С.А. Богданов |
| Analysis | Full AI Review Included |
Executive Summary
Section titled “Executive Summary”This research details the successful fabrication and characterization of periodic, multilayer Nitrogen-Vacancy (NV) center nanostructures within single-crystal Chemical Vapor Deposition (CVD) diamond, targeting applications in quantum sensing.
- Ultra-Sharp Interfaces: The CVD process achieved nitrogen-doped delta-layers with exceptionally sharp boundaries, measured to be less than 1 nm thick, confirmed via Secondary Ion Mass Spectrometry (SIMS).
- Enhanced NV- Signal: Multilayer structures demonstrated a significant increase in the practically important NV- photoluminescence (PL) signal intensity compared to uniformly doped diamond layers with similar total nitrogen surface density.
- Preserved Coherence: The spin coherence time (T2) remained high (up to 7.0 µs), comparable to or exceeding typical values for uniformly doped layers, indicating high material quality and low paramagnetic impurity concentration.
- Optimized Structure: The study shows that the ratio of NV-/NV0 centers is influenced by the distance between the doped layers, suggesting that neighboring nitrogen donors affect the charge state recombination dynamics.
- Methodological Advancement: The technique utilizes a specialized CVD reactor and low methane concentration (0.15%) growth conditions to ensure slow growth and atomically smooth surfaces, critical for precise delta-doping.
Technical Specifications
Section titled “Technical Specifications”| Parameter | Value | Unit | Context |
|---|---|---|---|
| Interface Sharpness | < 1 | nm | Thickness of the nitrogen-doped layer boundary (SIMS profile). |
| Substrate Type | HPHT (100) | Orientation | High Pressure High Temperature diamond used as seed. |
| Substrate Misorientation Angle | 0.8-1.2 | ° | Angle relative to the [100] crystallographic direction. |
| Base Nitrogen Concentration (Substrate) | < 1015 | cm-3 | Background N concentration in the HPHT substrate. |
| Gas Mixture Pressure | 40 | Torr | CVD growth condition. |
| Total Gas Flow | 950 | sccm | CVD growth condition. |
| Methane Concentration (CH4) | 0.15 | % | Low concentration ensures slow, atomic-smooth growth regime. |
| Nitrogen Concentration (N2) | 0.5-1.5 | % | Doping gas concentration during layer growth. |
| T2 Coherence Time (Max, Sample NV7) | 7.0 | µs | Measured using spin echo technique. |
| T2 Coherence Time (Min, Sample S39) | 4.2 | µs | Measured using spin echo technique. |
| NV-/NV0 Ratio (S39, S17) | ~1.8 | Ratio | Similar to uniformly doped sample S14. |
| NV-/NV0 Ratio (NV7) | 1.3 | Ratio | Lower ratio observed in structures with greater layer separation. |
| Excitation Wavelength | 514 | nm | DPSS laser used for PL and T2 measurements. |
| Excitation Power | 100 | mW | Power used for PL measurements. |
| Sample S39: Layer Thickness | 12 | nm | Thickness of individual doped layers. |
| Sample S39: Period | 39 | nm | Distance between doped layers. |
| Sample S39: N Concentration in Layer | 8.6 x 1018 | cm-3 | Nitrogen concentration within the doped layer. |
Key Methodologies
Section titled “Key Methodologies”The multilayer NV-center structures were fabricated and analyzed using the following specialized techniques:
- CVD Growth: Performed in a specialized CVD reactor previously developed for Boron delta-doping [5].
- Substrate Preparation: HPHT (100) diamond substrates were polished to achieve a precise misorientation angle (0.8-1.2°) to control nitrogen incorporation during growth.
- Growth Recipe: Slow growth rate was ensured by maintaining a low methane concentration (0.15%) to achieve atomically smooth CVD diamond surfaces [3].
- Doping Control: Periodic nitrogen doping was achieved by varying the N2 concentration (0.5-1.5%) in the gas mixture (H2/CH4) during the growth sequence.
- Nitrogen Profiling (SIMS): Concentration profiles were measured using Time-of-Flight Secondary Ion Mass Spectrometry (TOF.SIMS-5).
- Data Correction: Raw SIMS data was corrected using a methodology that accounts for the Depth Resolution Function (DRF) to accurately reconstruct the true nitrogen concentration profile [8].
- Photoluminescence (PL) Spectroscopy: Spectra were measured using a Horiba Jobin Yvon FHR-1000 spectrometer with a 514 nm DPSS laser (1W max power).
- Signal Isolation: The intensity of the NV- (637 nm) and NV0 (575 nm) zero-phonon lines (ZPLs) was measured relative to the broadband phonon sideband, allowing for clean isolation of the ZPL signal.
- Spin Coherence (T2) Measurement: Conducted using a confocal microscope setup [9] and the spin echo technique. Electron spin manipulation was performed using a 2-loop antenna (200 µm diameter).
Commercial Applications
Section titled “Commercial Applications”The development of precisely controlled, multilayer NV-center nanostructures in diamond is critical for several high-value commercial and research applications:
- High-Sensitivity Magnetometry: Creating sensors with high spatial resolution and enhanced signal intensity (due to increased NV- concentration) while maintaining long spin coherence times (T2).
- Bio-Sensing and Imaging: Utilizing NV centers as biocompatible sensors for high-resolution temperature sensing and magnetic field mapping within biological systems.
- Quantum Information Technology: Providing the foundational material for solid-state quantum computing and memory architectures that require NV centers to be placed with nanometer precision.
- Advanced Diamond Electronics: Engineering diamond materials with tailored, depth-dependent electronic properties for specialized semiconductor and high-power RF devices.
View Original Abstract
Results of synthesis of multilayered nitrogen doped nanostructures, which consist of periodically located nitrogen-containing layers in monocrystalline CVD diamond, are presented. The possibility of creation of nitrogen doped layers with extremely abrupt interfaces, less than 1 nm, is demonstrated. Photoluminescence studies have shown that multilayered structures allow obtaining higher emission intensity of practically important NV- centers with spin coherence times close to homogeneously doped layers at the same nitrogen concentration.