Enhancing the brightness of electrically driven single-photon sources using color centers in silicon carbide
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2018-02-13 |
| Journal | npj Quantum Information |
| Authors | Igor A. Khramtsov, Andrey A. Vyshnevyy, Dmitry Yu. Fedyanin |
| Institutions | Moscow Institute of Physics and Technology |
| Citations | 44 |
| Analysis | Full AI Review Included |
Technical Analysis and Documentation for 6CCVD
Section titled âTechnical Analysis and Documentation for 6CCVDâExecutive Summary
Section titled âExecutive SummaryâThe research details a theoretical and numerical study demonstrating the potential for ultra-bright, electrically pumped single-photon sources (SPS) leveraging the Silicon antisite-stacking fault (SiC-SF) color center in 4H-SiC.
- Record Room Temperature Brightness: Rigorous simulations confirm that electrically driven SiC color centers can achieve a photon emission rate superior to electrically driven diamond NV centers or epitaxial quantum dots at ambient conditions (300 K).
- High Performance Achieved: The p+-n-n+ SiC diode structure, mimicking experimental results, reproduces single-photon emission rates up to 40 Mcps, accurately accounting for self-heating effects that cause non-linear current dependence.
- Gigahertz Potential: Through optimizationâincluding grading the doping profile and integrating optical nanoantennas for Purcell enhancement (reducing the radiative lifetime, $\tau$r)âemission rates of 5-10 Gcounts/s are predicted.
- Critical Mechanism: High emission efficiency is governed by optimizing electron and hole capture rates, requiring the color center to be positioned precisely within a narrow transition region (approx. 150 nm width) of the junction.
- Engineering Challenge Identified: Device self-heating (raising temperature to ~380 K) is a key limiting factor at high injection currents, underscoring the need for materials with superior thermal management properties.
- CMOS Compatibility: The entire system utilizes SiC, laying a foundation for scalable, practical quantum devices produced in established CMOS processes.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Predicted Max Emission Rate (Optimized) | 5-10 | Gcounts/s | Requires Purcell effect and optimized p-i-n structure |
| Achieved Emission Rate (Experiment/Simulated) | ~40 | Mcps | At high current (1.84 A/cm2) and T = 380 K |
| Doping Concentration (N+ Substrate) | 7 x 1019 | cm-3 | Nitrogen (Donor) |
| Doping Concentration (N Epilayer) | 4 x 1015 | cm-3 | Nitrogen (Donor) |
| Operating Temperature Range | 300 - 380 | K | Ambient to Self-Heated |
| High Injection Current Density | 1.84 | A/cm2 | Used for high-power simulations |
| Bulk Radiative Lifetime ($\tau$r) | 3.6 | ns | Excited state lifetime in bulk 4H-SiC |
| Target Radiative Lifetime ($\tau$r) | 70 | ps | Reduced by Purcell Factor ~50x (Required for GigaHertz) |
| Critical Transition Region Width | ~150 | nm | Spatial region necessary for efficient single-photon emission |
| Electron Capture Cross-Section ($\sigma$n) | 6.1 x 10-15 | cm2 | Calculated for the transition region |
Key Methodologies
Section titled âKey MethodologiesâThe theoretical and numerical study relied on rigorous modeling of the electrical and optical processes in the SiC diode:
- Device Structure Modeling: 2D numerical simulations were performed on a p+-n-n+ 4H-SiC diode structure, incorporating a non-uniform acceptor distribution (Aluminum implantation) in the p-type layer.
- Carrier Transport Simulation: Self-consistent steady-state solutions were obtained for Poissonâs equation, semiconductor drift-diffusion equations, and carrier continuity equations using nextnano++ software to map electron ($n$) and hole ($p$) densities.
- Electroluminescence (EL) Mechanism: The SiC-SF color center was modeled using three essential states: neutral ground (g0>), neutral excited (e0>), and positively charged (g+>), linked by electron and hole capture processes (Cn and Cp).
- Kinetic Rate Equations: A system of four coupled differential equations (Eq. 1) was solved to determine the steady-state populations of the excited, shelving, and charged states, revealing the crucial role of the long-lived shelving state ($\tau$s ~35 ns).
- Self-Heating Inclusion: Device temperature rise (proportional to current density squared, $J$2) was incorporated to accurately model the non-linear increase in carrier densities and the subsequent linear (unsaturated) growth of the emission rate observed experimentally at high currents.
- Optimization Proposal: A p-i-n diode with a graded doping profile in the i-region was proposed to maximize the overlap between the high-density electron/hole region and the implanted color center, targeting maximum capture rates.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & Capabilitiesâ6CCVD provides the precision diamond materials and engineering services necessary to replicate, extend, or improve upon this quantum electro-optic research, particularly by leveraging the superior thermal and optical characteristics of MPCVD Single Crystal Diamond (SCD).
| Application Requirement | 6CCVD SCD/PCD Material Solution | 6CCVD Engineering & Value Proposition |
|---|---|---|
| Material Host for Color Centers | Optical Grade Single Crystal Diamond (SCD): Offers ultra-high thermal conductivity (5x better than SiC), crucial for mitigating the self-heating effects identified in the paper at GigaHertz pump currents (T > 380 K). | SCD enables stable, high-power operation by minimizing thermal stress and ensuring consistent defect properties, maximizing reliability for electrically driven SPS. Polishing quality available: Ra < 1nm. |
| Junction Development (p+/n/n+ Analogs) | Custom Boron-Doped Diamond (BDD): We supply precisely controlled thicknesses (0.1”m - 500”m) of BDD films (P-type) and N-doped SCD films (N-type) for building analogous p-i-n or p-n junction structures. | Achieve the narrow, critical transition/injection region required (~150 nm in the SiC study) through highly controlled MPCVD layer growth and custom doping profiles for diamond quantum diodes. |
| High-Efficiency Light Extraction | Custom Substrates and Dimensions: Plates and wafers up to 125mm (PCD) or large SCD plates are available for integration with optical elements, matching the paperâs requirement for external structures like nanoantennas. | Facilitate the implementation of Purcell enhancement factors (50x - 200x reduction in $\tau$r) necessary to reach the 5-10 Gcounts/s regime. |
| Ohmic Contact Integration | In-House Metalization Services: 6CCVD offers deposition and patterning of standard electrodes (Ti/Pt/Au/W/Cu) required for creating low-resistance ohmic contacts (p+ and n+) for efficient electrical injection into the quantum device structure. | Streamline device fabrication by providing integrated material and electrode solutions, ensuring optimal carrier delivery crucial for high-current operation. |
| Custom Geometry & Prototyping | Precision Laser Cutting and Etching: Specialized services allow for shaping wafers and creating custom micro-structures necessary for subsequent plasma etching or optical integration of high-Q cavities and nanoantennas. | Rapidly transition from simulation results to physical prototype by ensuring precise dimensional control over the active device area (< 20 ”m contact size suggested). |
| Research Extension | PhD Engineering Support: Our in-house technical team specializes in quantum defect engineering (NV, SiV, etc.) and can consult on material selection and crystal orientation required to translate SiC methodologies to the diamond platform. | Leverage our expertise to minimize R&D cycles when developing next-generation diamond-based electrically driven quantum light sources. |
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Abstract Practical applications of quantum information technologies exploiting the quantum nature of light require efficient and bright true single-photon sources which operate under ambient conditions. Currently, point defects in the crystal lattice of diamond known as color centers have taken the lead in the race for the most promising quantum system for practical non-classical light sources. This work is focused on a different quantum optoelectronic material, namely a color center in silicon carbide, and reveals the physics behind the process of single-photon emission from color centers in SiC under electrical pumping. We show that color centers in silicon carbide can be far superior to any other quantum light emitter under electrical control at room temperature. Using a comprehensive theoretical approach and rigorous numerical simulations, we demonstrate that at room temperature, the photon emission rate from a p-i-n silicon carbide single-photon emitting diode can exceed 5 Gcounts/s, which is higher than what can be achieved with electrically driven color centers in diamond or epitaxial quantum dots. These findings lay the foundation for the development of practical photonic quantum devices which can be produced in a well-developed CMOS compatible process flow.
Tech Support
Section titled âTech SupportâOriginal Source
Section titled âOriginal SourceâReferences
Section titled âReferencesâ- 2003 - Silicon Carbide: Materials, Processing & Devices