Optically detected magnetic resonance of silicon vacancies in 4H-SiC at elevated temperatures toward magnetic sensing under harsh environments

Abstract

Negatively charged silicon vacancy (VSi-) defects in silicon carbide are expected to be used for magnetic sensors under harsh environments, such as space and underground due to their structural stability and potential for high-fidelity spin manipulation at high temperatures. To realize VSi- based magnetic sensors operating at high temperatures, the temperature dependence of optically detected magnetic resonance (ODMR) in the ground states of VSi- defects, which is the basic principle of magnetic sensing, should be systematically understood. In this work, we demonstrate the potential of VSi- magnetic sensors up to at least 591 K by showing the ODMR spectra with different temperatures. Furthermore, the resonance frequency of the ground level was independent of temperature, indicating the potential for calibration-free magnetic sensors in temperature-varying environments. We also characterize the concentration of VSi- defects formed by electron irradiation and clarify the relationship of magnetic sensing sensitivity to VSi- concentration and find that the sensing sensitivity increases linearly with VSi- concentration up to at least 6.0 × 1016 cm-3. The magnetic sensitivity at a temperature above 549 K was reduced by half as compared to that at 300 K. The results pave the way for the use of a highly sensitive VSi-based magnetic sensor under harsh environments.