Calculation of spin-Hamiltonian constants for extended defects (Vsᵢ-Vc)⁰ (Ky5) in silicon carbide polytype 3C-SiC

Abstract

This work presents theoretical studies of the neutral divacancy, i.e., the Ky5 center that is one of the dominant defects in 3C-SiC bulk crystals subjected to relatively high doses of neutron irradiation. Being the paramagnetic center, the extended defect Ky5 shows the value of the zero field splitting (ZFS) in the electron paramagnetic resonance (EPR) signal D = 443⋅10⁻⁴cm⁻¹ and 454⋅10⁻⁴cm⁻¹ in two modifications. To understand the ZFS value, a relativistic ab initio calculation has been carried out to obtain the electron structure of the 3C-SiC crystal containing the defect Ky5. Using the WIEN program package, the self-consistent values of the electron density ρ and controlling ρ potential V have been found. Based on the obtained values ρ and V, the contributions in ZFS from dipole-dipole and spin-orbit interactions have been found. It has been shown that the main contribution stems from the dipole-dipole interaction. Spin-orbit interaction gives a negligible contribution to ZFS. Due to the relativistic approach, spin-up and spin-down values of the electron density have been obtained, which permits to calculate the hyperfine fields at the nuclei in the environment of the divacancy in 3C-SiC.