Supplementary Material: 1 Fabrication of high-brightness silicon vacancy color-center 2 ensembles in 4H-SiC via MeV particles

The supplementary material outlines the fabrication and characterization of high-brightness silicon vacancy (VSi) color-center ensembles in 4H-Silicon Carbide (SiC) using MeV particle irradiation. The goal of the study was to optimize the creation of VSi centers in 4H-SiC, which are essential for quantum information and sensing applications.

Key points from the supplementary material:

1. Sample Preparation and Characterization:

• The 4H-SiC samples were pretreated by annealing at 900°C and 1100°C, which helped eliminate defects such as VSi-10 centers, enhancing homogeneity across samples. The photoluminescence (PL) spectra were measured before and after annealing, showing significant improvement in the material's uniformity.

2. Ion Etching and X-ray Photoelectron Spectroscopy (XPS):

• Ion etching was performed using 500 eV Ar⁺ ions to remove surface layers. XPS analysis revealed that ion etching removed surface oxides effectively, and the Si-C bond peak shifted after etching, confirming successful surface modification.

3. Laser-Driven Ion Energy Spectrum:

• The laser-accelerated ion energy spectrum demonstrated that protons and carbon ions had cutoff energies around 3 MeV for protons and 4 MeV for carbon ions. This spectrum is important for understanding the displacement damage caused by ion irradiation.

4. Confirmation of VSi-10 Centers:

• Low-temperature (LT) PL measurements confirmed the creation of VSi-10 centers, which were observed through sharp peaks corresponding to the zero-photon line (ZPL). The results are consistent with previous studies on VSi centers.

5. Optically Detected Magnetic Resonance (ODMR):

• ODMR measurements at room temperature were used to confirm the existence of VSi-2 centers. The resonance peak splitting observed in the ODMR spectra under increasing magnetic field strength matched theoretical calculations, providing confirmation of the VSi-2 centers.

6. SRIM Calculation for Displacement Damage in SiC:

• The SRIM (Stopping and Range of Ions in Matter) calculations were used to estimate the displacement damage caused by different energetic ions in SiC. The study compared the damage caused by protons, carbon ions, and electrons, and calculated the average vacancy density along the depth, providing insight into how different ions impact SiC at various energies.

7. Room-Temperature Photoluminescence of High-Temperature Irradiated Samples:

• The PL spectra of samples irradiated with 1 MeV protons at different fluences were measured to observe the effects of irradiation temperature on the creation of VSi centers. The results showed that high-temperature irradiation influenced the PL intensity and characteristics of VSi centers.

Conclusion:
The study demonstrates the effective fabrication of high-brightness VSi centers in 4H-SiC via MeV particle irradiation. The use of ion etching, combined with PL, XPS, ODMR, and SRIM analyses, allows for the detailed characterization of these centers, which are critical for future quantum applications. The results suggest that the VSi-10 centers in 4H-SiC can be used in advanced quantum information processing and sensing technologies.