Structure of the silicon vacancy in6H−SiCafter annealing identified as the carbon vacancy–carbon antisite pair

Abstract

We investigated radiation-induced defects in neutron-irradiated and subsequently annealed 6H-silicon carbide ͑SiC͒ with electron paramagnetic resonance ͑EPR͒, the magnetic circular dichroism of the absorption ͑MCDA͒, and MCDA-detected EPR ͑MCDA-EPR͒. In samples annealed beyond the annealing temperature of the isolated silicon vacancy we observed photoinduced EPR spectra of spin Sϭ1 centers that occur in orientations expected for nearest neighbor pair defects. EPR spectra of the defect on the three inequivalent lattice sites were resolved and attributed to optical transitions between photon energies of 999 and 1075 meV by MCDA-EPR. The resolved hyperfine structure indicates the presence of one single carbon nucleus and several silicon ligand nuclei. These experimental findings are interpreted with help of total energy and spin density data obtained from the standard local-spin density approximation of the density-functional theory, using relaxed defect geometries obtained from the self-consistent charge density-functional theory based tight binding scheme. We have checked several defect models of which only the photoexcited spin triplet state of the carbon antisite-carbon vacancy pair (C Si -V C ) in the doubly positive charge state can explain all experimental findings. We propose that the (C Si -V C ) defect is formed from the isolated silicon vacancy as an annealing product by the movement of a carbon neighbor into the vacancy.

Ab initiostudy of the migration of intrinsic defects in3C−SiC

“…We consider this as a good agreement taking the variation of the levels among the different polytypes and the inequivalent lattice sites into account (it was not stated in Ref. 20 to which site the calculations referred).…”

“…Using a LMTO-ASA Greens function approach based on DFT and LSDA Lingner et al 20 obtain similar results for 6H-SiC. A metastability of the silicon vacancy is also predicted by their calculations.…”

EPR andab initiocalculation study on the EI4 center in4H- and6H-SiC

“…The transformation from V Si to C Si V C has been previously predicted by theoretical calculations. 19 This process seems to be dominating in the temperature range below 600°C. In this temperature range, the signals of the EI4 center and the neutral divacancy 20 slightly increase.…”

Electrically Driven Spin Resonance in Silicon Carbide Color Centers

“…This imaging applies to GHz-frequency resonant electric fields, 2 complementing non-resonant kHz-frequency AC electric field sensing previously demonstrated with NV centers in diamond [3]. Since the QL1 defect shares a ground-state spin Hamiltonian with many intrinsic defects in 13,15,[26][27][28][29] and the NV center in diamond [4], our results apply to a broad class of optically addressable solid-state defects.Our E-ODMR measurements determine that the optically addressable spin of QL1 has integervalue total spin (S), and long spin relaxation (T 1 ) times [10] suggest that it is the orbital ground state (see SI). Together with its similar optical and spin transition energies to the S=1 neutral divacancies in 4H-SiC [8,9], QL1 is likely to be an S=1 neutral divacancy as well.…”

“…This imaging applies to GHz-frequency resonant electric fields, 2 complementing non-resonant kHz-frequency AC electric field sensing previously demonstrated with NV centers in diamond [3]. Since the QL1 defect shares a ground-state spin Hamiltonian with many intrinsic defects in 13,15,[26][27][28][29] and the NV center in diamond [4], our results apply to a broad class of optically addressable solid-state defects.…”