Electronic structure and magneto-optical properties of silicon-nitrogen-vacancy complexes in diamond
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2020-09-01 |
| Journal | Physical review. B./Physical review. B |
| Authors | Marcin Roland ZemĹa, Kamil Czelej, Paulina KamiĹska, Chris G. Van de Walle, Jacek A. Majewski |
| Institutions | University of Warsaw, Warsaw University of Technology |
| Citations | 21 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive Summaryâ- Quantum Emitter Identification: The neutral silicon-nitrogen-vacancy complex (SiNV0) is identified as a highly promising, robust single-photon emitter (SPE) operating at 1530 nm.
- Telecom Compatibility: The 1530 nm emission wavelength falls directly within the C band of telecommunication, making SiNV0 attractive for scalable quantum communication networks.
- High Efficiency: SiNV0 exhibits a high Debye-Waller (DW) factor of 46%. This indicates that a large fraction of emitted photons are concentrated in the Zero-Phonon Line (ZPL), which is critical for efficient quantum light sources.
- Shallow Donor Potential: The SiN dimer defect acts as a shallow donor in diamond, possessing a donor level (E+1/0) calculated at 0.57 eV below the Conduction Band Minimum (CBM). This value is comparable to substitutional phosphorus, suggesting a viable path toward achieving n-type diamond conductivity.
- Formation Stability: Thermodynamic calculations confirm a strong binding energy and a driving force for the complexing of Si and N atoms with vacancies (V), ensuring the stability of SiN, SiNV, and SiN2V complexes once formed.
- Synthesis Pathway: Complex formation requires non-equilibrium introduction (e.g., ion implantation) followed by annealing, utilizing the relatively low migration barriers of interstitial nitrogen (1.7 eV, above 600 °C) and vacancies (2.7 eV, above 800 °C).
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| SiNV0 ZPL Emission Energy | 0.81 | eV | Corresponds to the lowest energy optical transition. |
| SiNV0 Emission Wavelength | 1530 | nm | C band telecom wavelength. |
| SiNV0 Total Huang-Rhys Factor (S0) | 0.775 | Dimensionless | Describes the strength of electron-phonon coupling. |
| SiNV0 Debye-Waller (DW) Factor (WZPL) | 46 | % | Fraction of photons emitted into the ZPL (high efficiency). |
| SiN Dimer Donor Level (E+1/0) | 0.57 | eV | Below the CBM; comparable to shallow phosphorus donor. |
| SiN Dimer Acceptor Level (E0/-) | 0.32 | eV | Below the CBM. |
| Vacancy Migration Barrier (ÎEVm) | 2.7 | eV | Required energy for vacancy diffusion (initiates around 800 °C). |
| Interstitial Nitrogen Migration Barrier (ÎENm) | 1.7 | eV | Required energy for nitrogen diffusion (initiates above 600 °C). |
| SiNV Quasi-Local Mode (aâ) | 480 | cm-1 | Symmetric stretching mode (IPR=0.116). |
| SiNV Quasi-Local Mode (aâ) | 435 | cm-1 | Bending mode (IPR=0.055). |
| SiN Dimer Quasi-Local Mode (e) | 477 | cm-1 | Doubly degenerate mode. |
Key Methodologies
Section titled âKey MethodologiesâThe study relied entirely on advanced computational methods, primarily Density Functional Theory (DFT), to predict material properties:
- Electronic Structure and Energetics: Spin-polarized hybrid DFT calculations were performed using the HSE06 functional (implemented in VASP) on large 512-atom supercells to determine Kohn-Sham eigenvalues and defect formation energies.
- Charged Defect Correction: The formation energies of charged defects were calculated using established correction schemes (e.g., FNV method) to accurately reference the Fermi level to the Valence Band Maximum (VBM).
- Excited State Analysis: The potential energy surface (PES) and atomic relaxation energies upon optical excitation were calculated using the constrained DFT (ASCF) method.
- Vibrational Spectra: Density Functional Perturbation Theory (DFPT) was employed using the PBE functional to calculate phonon spectra, applying a strict 10-4 eV/A force convergence criterion for high precision of quasi-local modes.
- Vibronic Coupling and Luminescence: The photoluminescence (PL) spectrum and electron-phonon coupling were modeled using the theory of Huang and Rhys (HR), which calculates the spectral function based on partial Huang-Rhys factors (Sk).
- Hyperfine Interactions: Hyperfine tensors were calculated using the frozen-valence approximation, including core spin polarization effects, with a high plane-wave cutoff energy of 800 eV.
- Migration Barriers: Minimum energy pathways (MEP) for interstitial nitrogen and vacancy diffusion were determined using the climbing-image nudged-elastic-band (CI-NEB) method.
Commercial Applications
Section titled âCommercial Applicationsâ- Quantum Computing and Memory: SiNV0 is a strong candidate for solid-state qubits and quantum memory elements due to its stability and potential for spin manipulation (paramagnetic doublet S = 1/2 state).
- Fiber Optic Quantum Communication: The precise 1530 nm emission wavelength allows SiNV0 to be directly integrated into existing commercial fiber optic infrastructure (C band), enabling long-distance quantum key distribution (QKD) and quantum networking.
- Advanced Diamond Semiconductors: The discovery that the SiN dimer acts as a shallow donor (0.57 eV) provides a critical pathway for manufacturing stable, high-quality n-type diamond, necessary for high-power, high-frequency, and high-temperature electronic devices.
- Single-Photon Source Manufacturing: The high Debye-Waller factor (46%) makes SiNV0 suitable for mass production of bright, efficient single-photon sources required for photonic quantum technologies.
- Quantum Sensing and Magnetometry: The paramagnetic nature of SiNV0 allows for detection via Electron Paramagnetic Resonance (EPR), supporting applications in high-resolution magnetic field sensing, similar to the established NV center.
View Original Abstract
The silicon-vacancy (SiV) and nitrogen-vacancy (NV) centers in diamond are commonly regarded as prototypical defects for solid-state quantum information processing. Here we show that when silicon and nitrogen are simultaneously introduced into the diamond lattice these defects can strongly interact and form larger complexes. Nitrogen atoms strongly bind to Si and SiV centers and complex formation can occur. Using a combination of hybrid density functional theory (DFT) and group theory, we analyze the electronic structure and provide various useful physical properties, such as hyperfine structure, quasi-local vibrational modes, and zero-phonon line, to enable experimental identification of these complexes. We demonstrate that the presence of substitutional silicon adjacent to nitrogen significantly shifts the donor level toward the conduction band, resulting in an activation energy for the SiN center that is comparable to phosphorus. We also find that the neutral SiNV center is of particular interest due to its photon emission at $\sim$1530 nm, which falls within the C band of telecom wavelengths, and its paramagnetic nature. In addition, the optical transition associated with the SiNV$^0$ color center exhibits very small electronâphonon coupling (HuangâRhys factor~=~0.78) resulting in high quantum efficiency (Debye-Waller factor = 46%) for single-photon emission. These features render this new center very attractive for potential application in scalable quantum telecommunication networks.