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内容記述 |
Spin-active defects in wide bandgap semiconductors have emerged as promising platforms for quantum information technologies and quantum sensing. In particular, the spins of certain types of divacancies (PL1 and PL3)1 and divacancy-related defects (PL5, PL6, and PL7)1,2 in 4H-SiC can be optically initialized and read out, and maintain spin coherence at room temperature. Among these, PL5–7—whose microscopic structures remain unidentified—have been reported to show high single-spin contrast (10–30%) in optically detected magnetic resonance (ODMR). Their contrasts significantly exceed that of silicon vacancy centers (2–6%) in 4H-SiC, another well-studied spin-active defect operatable at room temperature. These characteristics make divacancy-related defects attractive spin-system candidates for quantum technologies.However, divacancy and divacancy-related defects emit in the near-infrared (NIR) spectral range (λ > 1000 nm), which lies outside the sensitivity range of silicon-based photodetectors, and detection using typical NIR detectors tends to suffer from low efficiency and high dark noise. This makes optical detection of these defects challenging and motivates the exploration of alternative approaches that are not constrained by photodetector performance.Photocurrent-detected magnetic resonance (PDMR)6 is an electrical detection method that circumvents the limitations of photodetectors. In this technique, laser illumination ionizes the defects, generating a photocurrent that is collected via electrodes for spin-state readout. PDMR is a coherent detection technique compatible with quantum spin control, and notably, it has recently demonstrated single-spin sensitivity superior to that of conventional ODMR for negatively charged silicon vacancies in 4H-SiC. This result raises the expectation that similarly high sensitivity may also be achievable for other types of defects. However, to date, PDMR has only been demonstrated for negatively charged nitrogen-vacancy centers in diamond and negatively charged silicon vacancy centers in 4H-SiC.While applying PDMR to divacancy and divacancy-related defects in 4H-SiC remains an open and desirable challenge, the applicability of photoelectrical detection to PL5–7 is nontrivial. This is mainly due to their reported superior photostability compared to the structurally identified and well-studied divacancies (PL1–4), which has been tentatively attributed to their robustness against photo ionization, even though PL5–7’s ionization pathways remain poorly understood. In this study, we study the photo current response from a 4H-SiC sample containing divacancy and divacancy-related defects to explore the applicability of photo electrical detection. |
