Thermal Stability of Spin Defects in a 6H-SiC Crystal According to Photoluminescence and Electron Paramagnetic Resonance Data

The spin and optical properties of two main types of spin defects (nitrogen vacancy (NV) centers and divacancies) in an isotopically purified crystal 6H-²⁸SiC at different temperatures of the sample have been studied using the high-frequency electron paramagnetic resonance method and the luminescence analysis. It has been established that the ratio of the intensity of electron paramagnetic resonance signals from divacancies to the intensity of signals from NV defects decreases monotonically with an increase in the crystal temperature from 40 to 140 K, and signals from divacancies are no longer observed at temperatures above 140 K. The analysis of the optical characteristics of defects under the variation of the crystal temperature and the determination of activation energies have shown that all types of color centers, regardless of their position in the crystal lattice and the type of symmetry (C_1h and \({{C}_{{3{v}}}}\)), have a mechanism for thermal quenching of luminescence. The obtained results indicate that electron qubits based on NV centers and divacancies can be simultaneously located within one silicon carbide matrix, with the subsequent selective initialization, processing (evolution), and reading of the state of a certain single center.