Cathodoluminescence Characterization of Point Defects Generated through Ion Implantations in 4H-SiC
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2023-05-26 |
| Journal | Coatings |
| Authors | Enora Vuillermet, Nicolas Bercu, Florence Etienne, Mihai Lazar |
| Institutions | Université de Reims Champagne-Ardenne, Laboratoire de Recherche en Nanosciences |
| Citations | 7 |
| Analysis | Full AI Review Included |
Cathodoluminescence Characterization of Point Defects Generated through Ion Implantations in 4H-SiC
Section titled âCathodoluminescence Characterization of Point Defects Generated through Ion Implantations in 4H-SiCâExecutive Summary
Section titled âExecutive SummaryâThis study investigates the controlled generation and characterization of silicon vacancy (VSi) and divacancy (VCVSi) color centers in 4H-SiC using ion implantation and subsequent annealing, focusing on optimizing defect configuration for quantum applications.
- Controlled Defect Generation: Silicon vacancies (VSi) were generated in 4H-SiC epilayers via successive ion implantations of Nitrogen (N) and Aluminum (Al) dopants, characterized using Cathodoluminescence (CL) at 80K.
- Pre-Annealing Configuration: Directly after implantation, VSi defects preferentially occupied the higher excited state (V1â at 856 nm, hexagonal site), particularly favored by high-energy and high-temperature N implantation.
- Annealing Effect (900 °C): Post-implantation annealing (900 °C for 15 min under Ar) caused VSi to shift to the more stable V1 configuration (862 nm), which became the dominant peak.
- Divacancy Formation: Annealing also led to the generation of divacancy defects (VCVSi), identified by Zero Phonon Lines (ZPLs) in the NIR range (e.g., PL4 at 1080 nm).
- Defect Proportionality: A strong linear proportionality was observed between the CL intensity of the V1 peak and the PL4 divacancy peak, confirming that VSi must be in the stable V1 configuration to form VCVSi divacancies.
- Optimal Conditions: Highest CL intensity for both V1 and PL4 defects was achieved using high-dose N implantation (1.88 x 1015 cm-2) at room temperature (RT), suggesting that controlled lattice damage aids in subsequent stable defect formation upon annealing.
- Process Compatibility: The 900 °C annealing temperature is compatible with standard thermal steps used in 4H-SiC device fabrication (e.g., ohmic contact annealing), facilitating integration into commercial device flows.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Substrate Polytype | 4H-SiC | NA | n-type, 8°1â off-axis wafer |
| Epilayer Thickness | 10 | ”m | Nitrogen doped |
| Background Doping (N) | 8.80 x 1015 | cm-3 | Epilayer concentration |
| Implantation Ions | Nitrogen (N) and Aluminum (Al) | NA | N (n-type dopant), Al (p-type dopant) |
| Implantation Energy Range | 20 to 400 | keV | Used for depth control |
| Implantation Dose Range | 6.81 x 1011 to 5.4 x 1015 | cm-2 | Total dose varies by sample |
| Annealing Temperature | 900 | °C | Rapid Thermal Process (RTP) |
| Annealing Duration | 15 | min | Performed under Argon (Ar) |
| CL Measurement Temperature | 80 | K | Liquid nitrogen cooling |
| CL Excitation Voltage | 15 | kV | Electron beam voltage |
| CL Excitation Current | 1 | nA | Electron beam current |
| V1â ZPL Wavelength (VSi) | 856 | nm | Hexagonal site, higher excited state (h) |
| V1 ZPL Wavelength (VSi) | 862 | nm | Hexagonal site, stable state (h) |
| V2 ZPL Wavelength (VSi) | 912-919 | nm | Pseudo-cubic site (k) |
| PL4 ZPL Wavelength (VCVSi) | 1080 | nm | Divacancy defect (hk configuration) |
| V1/PL4 Intensity Relation | y = (2.78598 ± 0.07)x | NA | Linear proportionality after annealing |
Key Methodologies
Section titled âKey MethodologiesâThe generation and characterization of point defects were achieved through a controlled sequence of ion implantation and thermal processing steps:
- Surface Preparation: 4H-SiC samples (10 ”m n-doped epilayer) were immersed in hydrofluoric acid (HF) to remove any native or residual silicon dioxide (SiO2) layer prior to implantation.
- Ion Implantation: Successive ion implantations of N or Al were performed to create a homogeneous dopant profile. Parameters varied across samples, including energy (20-400 keV), dose (1011-1015 cm-2), and temperature (RT, 300 °C, 400 °C).
- Implantation Geometry: All implantations utilized a fixed tilt angle of 7° and a twist angle of 90° to minimize ion channeling effects.
- Concentration Modeling: Dopant and silicon vacancy concentration profiles were simulated using I2SiC software (Monte Carlo Binary Collision Approximation, BCA) to predict defect depth and concentration.
- Thermal Annealing: Samples were annealed at 900 °C for 15 minutes using a graphite resistive furnace (AET RTP) under an inert Argon (Ar) atmosphere. The heating rate was rapid (2 °C/s).
- Defect Characterization: Cathodoluminescence (CL) measurements were performed using a SPARC system coupled to a JEOL SEM. Measurements were taken at 80K (liquid nitrogen cooling) using a 15 kV, 1 nA electron beam to analyze ZPLs in the 800-1300 nm range.
Commercial Applications
Section titled âCommercial ApplicationsâThe controlled generation of stable, NIR-emitting point defects in 4H-SiC at process-compatible temperatures is highly relevant for emerging quantum technologies and advanced semiconductor manufacturing.
- Solid-State Quantum Computing: SiC divacancies (VCVSi) are leading candidates for solid-state spin qubits, exhibiting long spin coherence times (up to 5 seconds reported in literature), crucial for quantum memory and computation.
- Quantum Communication: The NIR emission range of VCVSi (1070-1140 nm) is close to the telecom O-band, making these defects suitable for generating quantum light sources compatible with existing fiber optic infrastructure.
- Integrated Quantum Photonics: Ion implantation allows precise control over the depth and lateral position of color centers, enabling the fabrication of integrated nanophotonic devices (e.g., nanobeam waveguides) that efficiently couple light from single-photon emitters.
- Quantum Sensing: Silicon vacancies (VSi) and divacancies can be used as highly sensitive quantum sensors for measuring magnetic fields, electric fields, or temperature within harsh environments, leveraging SiCâs high thermal stability and chemical inertness.
- Advanced Semiconductor Manufacturing: The defect activation annealing temperature (900 °C) is significantly lower than typical high-temperature doping activation steps (~1700 °C), allowing the defect generation step to be seamlessly integrated into existing commercial 4H-SiC device process flows (e.g., after ohmic contact formation).
View Original Abstract
The high quality of crystal growth and advanced fabrication technology of silicon carbide (SiC) in power electronics enables the control of optically active defects in SiC, such as silicon vacancies (VSi). In this paper, VSi are generated in hexagonal SiC (4H) samples through ion implantation of nitrogen or (and) aluminum, respectively the n- and p-type dopants for SiC. The presence of silicon vacancies within the samples is studied using cathodoluminescence at 80K. For 4H-SiC samples, the ZPL (zero phonon line) of the V1âČ center of VSi is more intense than the one for the V1 center before annealing. The opposite is true after 900 °C annealing. ZPLs of the divacancy defect (VCVSi) are also visible after annealing.
Tech Support
Section titled âTech SupportâOriginal Source
Section titled âOriginal SourceâReferences
Section titled âReferencesâ- 2017 - Review of Silicon Carbide Power Devices and Their Applications [Crossref]
- 2020 - Silicon Carbide Color Centers for Quantum Applications [Crossref]
- 2020 - Confocal Photoluminescence Characterization of Silicon-Vacancy Color Centers in 4H-SiC Fabricated by a Femtosecond Laser [Crossref]
- 2020 - Fundamental Research on Semiconductor SiC and Its Applications to Power Electronics [Crossref]
- 2021 - Novel Color Center Platforms Enabling Fundamental Scientific Discovery [Crossref]
- 2022 - Five-Second Coherence of a Single Spin with Single-Shot Readout in Silicon Carbide [Crossref]
- 2022 - Quantum Information Processing with Integrated Silicon Carbide Photonics [Crossref]