Photoelectrical Detection Characterizes PL3, PL5, PL6, and PL7 Spins in Silicon Carbide at Room Temperature

Silicon carbide holds immense promise for future quantum technologies, but effectively reading the information stored within its atomic defects remains a significant challenge. Naoya Morioka, Tetsuri Nishikawa, and colleagues at Kyoto University, alongside Hiroshi Abe from the National Institutes for Quantum Science and Technology and Takeshi Ohshima from Tohoku University, now demonstrate a new method for detecting these defects using electrical signals rather than light. Their work reveals strong, room-temperature detection of several key defects, including the divacancy (PL3) and PL5, PL6, and PL7 spin states, with PL7 and PL5 exhibiting particularly strong signals suitable for electrical readout. Importantly, the team uncovered a previously unknown property of the PL7 defect, revealing a secondary resonance, and definitively links recent observations of the PL3a defect to PL7, representing a key step towards realising practical electronic devices based on these silicon carbide defects.

Photoelectrical Detection of Silicon Carbide Spin Defects

This study pioneered a novel approach to detecting magnetic resonance using photoelectrical detection, offering a scalable alternative to traditional optical methods, especially for defects emitting in the near-infrared spectrum where photodetection can be difficult. Researchers successfully demonstrated room-temperature coherent photoelectrical detection of magnetic resonance from PL3, PL5, PL6, and PL7 spin defects within silicon carbide, revealing that PL7 and PL5 exhibit notably stronger signals than PL6, suggesting higher ionization efficiency and suitability for electrical readout applications. To distinguish between different spin defects and confirm the pairing of PL3a and PL7, scientists developed a two-frequency photoelectrical detection method, adapting a technique previously used to differentiate orientations of nitrogen-vacancy centers in diamond. Experiments confirmed that addressing PL3 with one microwave frequency resulted in a response solely at PL7, conclusively demonstrating that PL3a and PL7 represent the same defect.

From this pairing, the team extracted the zero-field splitting parameters of PL7, determining values of 1233. 6MHz and 99. 0MHz at room temperature. These clarified spin characteristics, alongside the observed ionization behavior, provide essential benchmarks for theoretical modeling of PL5-7, and could ultimately enable defect engineering for optimized performance.

Divacancies Dominate Silicon Carbide Defect Landscape

This research details the characterization of defects in silicon carbide (SiC) using optically detected magnetic resonance and pulsed-electron-spin-resonance techniques. The study meticulously identifies and characterizes several point defects in 4H-SiC, including PL5, PL3, and PL7, going beyond simple optical signatures to investigate their spin properties. Strong evidence suggests that divacancies, or pairs of missing atoms, are the primary origin of many of the observed defects, particularly PL3 and PL7, with variations in PL5 linked to different charge states and configurations of these divacancies. Researchers determined the spin state and symmetry of these defects, revealing how they interact with microwave fields, and highlighted the ability to control the charge state of these defects using optical excitation, significantly impacting their spin properties. The identified defects, with their well-defined spin states and optical properties, are promising candidates for building quantum sensors, qubits, and other quantum technologies.

Silicon Carbide Defect Spins Identified and Characterized

This work demonstrates room-temperature coherent photoelectrical detection of magnetic resonance from several point defects, PL3, PL5, PL6, and PL7, in silicon carbide. Notably, PL7 and PL5 exhibited stronger signals compared to PL6, indicating a greater efficiency in ionization and suggesting their suitability for electrical readout applications. Through detailed analysis, researchers identified PL7 as a spin-1 defect and precisely determined its zero-field splitting parameters, allowing for the definitive assignment of the previously debated PL3a defect to PL7. These clarified spin characteristics and ionization behaviors provide essential benchmarks for both theoretical modeling and future defect engineering efforts focused on PL5 and PL7. Electrical spin detection offers particular advantages for device integration and miniaturization, and further improvements in readout efficiency could pave the way for scalable quantum electronics based on defect spins in silicon carbide.