Cathodoluminescence Characterization of Point Defects Generated through Ion Implantations in 4H-SiC

At a Glance

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

Technical Documentation & Analysis: MPCVD Diamond for Quantum Emitters

This document analyzes the research paper “Cathodoluminescence Characterization of Point Defects Generated through Ion Implantations in 4H-SiC” and outlines how 6CCVD’s specialized MPCVD diamond materials and services can support, replicate, and advance this research, particularly in the field of solid-state quantum technologies.

Executive Summary

Core Research Focus: Generation and characterization of optically active point defects (silicon vacancies, V_Si, and divacancies, V_CV_Si) in 4H-SiC using controlled ion implantation (Nitrogen and Aluminum) for near-infrared (NIR) quantum light emission.
Key Methodology: Successive ion implantation followed by moderate thermal annealing (900 °C) under Argon atmosphere, characterized by Cathodoluminescence (CL) at 80K.
Critical Finding: Annealing shifts the silicon vacancy configuration from the excited V1’ state (856 nm) to the more stable V1 state (862 nm), simultaneously promoting the formation of divacancy defects (ZPLs 1080-1139 nm).
Process Validation: The study confirms that ion implantation and annealing at temperatures compatible with standard SiC device fabrication (900 °C) is a viable path for creating NIR-emitting color centers.
6CCVD Value Proposition: While SiC is a promising host, Single Crystal Diamond (SCD) is the superior material for quantum applications, offering significantly longer spin coherence times (e.g., 5 seconds for V_CV_Si in 4H-SiC vs. hours/days for NV centers in high-purity SCD).
Material Solution: 6CCVD provides high-purity, Optical Grade SCD substrates and custom Boron-Doped Diamond (BDD) layers, perfectly suited for high-fidelity ion implantation and subsequent nanophotonic device integration.

Technical Specifications

The following data points were extracted from the research detailing the experimental parameters and key results:

Parameter	Value	Unit	Context
Host Material Polytype	4H-SiC	N/A	n-type, 8°1’ off-axis wafer
Epilayer Thickness	10	µm	Initial nitrogen doping: 8.80 x 10¹⁵ cm^-3
Implantation Dopants	Nitrogen (N), Aluminum (Al)	N/A	Used to generate V_Si and V_CV_Si defects
Implantation Energy Range	20 to 400	keV	Successive implantations for homogeneous doping
Maximum Implantation Dose (N)	5.4 x 10¹⁵	cm^-2	Sample A17 (400 °C implant)
Implantation Temperatures	RT, 300, 400	°C	Room Temperature and elevated temperatures
Annealing Temperature	900	°C	Post-implantation defect recovery and recombination
Annealing Time	15	min	Performed under Argon (Ar) atmosphere
Characterization Method	Cathodoluminescence (CL)	N/A	Performed at 80K (Liquid Nitrogen cooling)
V_Si ZPL (V1’)	856	nm	Silicon Vacancy (excited state, favored before annealing)
V_Si ZPL (V1)	862	nm	Silicon Vacancy (stable state, favored after annealing)
V_CV_Si ZPL (PL4)	1080	nm	Divacancy defect (NIR emission)
V_Si Coherence Time (4H-SiC)	20	ms	Compared favorably to NV centers in SiC (1 µs)

Key Methodologies

The generation and characterization of point defects in 4H-SiC involved precise control over material processing and measurement conditions:

Substrate Preparation: Commercial 4H-SiC wafers with a 10 µm n-doped epilayer were cleaned using Hydrofluoric Acid (HF) to ensure removal of native silicon dioxide (SiO₂) prior to implantation.
Ion Implantation Strategy: Successive ion implantations (N and/or Al) were performed across multiple energy levels (20 to 400 keV) and doses (up to 5.4 x 10¹⁵ cm^-2) to create a homogeneous doped film and control the depth of generated defects.
Implantation Geometry: Fixed tilt (7°) and twist (90°) angles were maintained to control ion channeling effects. Elevated temperatures (300 °C, 400 °C) were used for some samples to minimize lattice damage and prevent amorphization.
Dopant and Vacancy Modeling: I2SiC simulation software (based on Monte Carlo/Binary Collision Approximation) was used to predict the concentration profiles of dopants and generated silicon vacancies (V_Si), validated against SIMS data.
Thermal Annealing: Samples underwent Rapid Thermal Processing (RTP) at 900 °C for 15 minutes under an inert Argon (Ar) atmosphere using a graphite resistive furnace, promoting defect recombination (V_Si + V_C -> V_CV_Si).
Defect Characterization: Cathodoluminescence (CL) measurements were performed at 80K using a SPARC system coupled to a SEM (15 kV, 1 nA) to identify the Zero Phonon Lines (ZPLs) of V_Si and V_CV_Si defects in the 800-1200 nm range.

6CCVD Solutions & Capabilities

This research demonstrates the feasibility of generating quantum emitters via ion implantation in wide-bandgap materials. 6CCVD specializes in the optimal host material—MPCVD Diamond—which offers superior performance for quantum applications, particularly concerning spin coherence and stability.

Applicable Materials for Quantum Emitter Research

6CCVD materials are engineered to meet the stringent requirements of quantum research, offering a direct pathway to higher-performance solid-state qubits compared to SiC.

Application Requirement	6CCVD Material Solution	Technical Rationale
High-Coherence Quantum Host	Optical Grade Single Crystal Diamond (SCD)	SCD is the gold standard for quantum defects (NV^-, SiV^-). Our high-purity SCD minimizes background defects, maximizing spin coherence time, which can exceed that of SiC defects by orders of magnitude.
Controlled Doping/Defect Generation	High-Purity SCD Substrates	Ideal for replicating the ion implantation methodology used in this paper to create NV centers (via N implantation) or SiV centers (via Si implantation).
Alternative Doping Studies	Boron-Doped Diamond (BDD)	Available for p-type conductivity studies or creating specific charge states of quantum defects, complementing the N/Al doping explored in SiC.

Customization Potential for Nanophotonic Device Fabrication

The fabrication of nanophotonic devices (as mentioned in the paper’s conclusion) requires materials with exceptional dimensional control and surface quality. 6CCVD provides the necessary engineering capabilities:

Custom Dimensions: We supply SCD plates and PCD wafers up to 125 mm in diameter, accommodating large-scale processing runs similar to the SiC wafers used in the study.
Precision Thickness Control: SCD and PCD layers are available from 0.1 µm to 500 µm, allowing researchers to precisely match the implantation depth profiles (e.g., using SRIM simulations) to the material thickness. Substrates up to 10 mm thick are available for bulk studies.
Ultra-Low Roughness Polishing: Ion implantation and subsequent nanophotonic patterning (e.g., etching nanobeams) demand pristine surfaces. 6CCVD guarantees Ra < 1 nm for SCD and Ra < 5 nm for inch-size PCD, minimizing surface scattering losses.
Integrated Metalization: The paper discusses device fabrication steps (ohmic contacts). 6CCVD offers in-house deposition of standard metal stacks, including Ti, Pt, Au, Pd, W, and Cu, allowing researchers to receive fully prepared, metalized substrates ready for lithography.

Engineering Support

6CCVD’s in-house PhD team specializes in MPCVD growth parameters and material selection for quantum applications. We can assist researchers in optimizing material specifications (e.g., nitrogen concentration, surface orientation, and thickness) for similar quantum emitter generation projects in diamond, ensuring maximum yield and coherence.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly. We offer global shipping (DDU default, DDP available) to ensure rapid delivery of high-quality diamond materials worldwide.

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 V1′ 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

Original Source

DOI: https://doi.org/10.3390/coatings13060992

References

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]