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EPR studies of the isolated negatively charged silicon vacancies in n -type 4 H - and 6 H -SiC: Identification of C <mml:…

2003; American Physical Society; Volume: 68; Issue: 16 Linguagem: Inglês

10.1103/physrevb.68.165206

1095-3795

Norikazu Mizuochi, Satoshi Yamasaki, H. Takizawa, N. Morishita, Takeshi Ohshima, H. Itoh, Junichi Isoya,

Semiconductor materials and interfaces

The isolated negatively charged silicon vacancy ${(V}_{\mathrm{Si}}^{\ensuremath{-}})$ in the hexagonal lattices of $4H$- and $6H\ensuremath{-}\mathrm{SiC}$ has been studied by electron paramagnetic resonance (EPR). The local structure was suggested to have ${T}_{d}$ symmetry from the isotropic g value within the resolution of the conventional X-band measurements, from the isotropic ${}^{29}\mathrm{Si}$ hyperfine interaction of the next-nearest-neighbor silicon atoms and from the absence of the zero-field splitting with the high spin state of $S=3/2.$ From the ${}^{13}\mathrm{C}$ hyperfine spectrum of the nearest-neighbor carbon atoms, the two kinds of ${V}_{\mathrm{Si}}^{\ensuremath{-}},$ denoted ${V}_{\mathrm{Si}}^{\ensuremath{-}}(\mathrm{I})$ and ${V}_{\mathrm{Si}}^{\ensuremath{-}}(\mathrm{II}),$ respectively have been distinguished. ${V}_{\mathrm{Si}}^{\ensuremath{-}}(\mathrm{I})$ and ${V}_{\mathrm{Si}}^{\ensuremath{-}}(\mathrm{II})$ are assigned to be arising from hexagonal site (h) and quasicubic sites $(k$ in $4H\ensuremath{-}\mathrm{SiC},$ ${k}_{1}$ and ${k}_{2}$ in $6H\ensuremath{-}\mathrm{SiC}),$ respectively. In both ${V}_{\mathrm{Si}}^{\ensuremath{-}}(\mathrm{I})$ and ${V}_{\mathrm{Si}}^{\ensuremath{-}}(\mathrm{II}),$ from the ${}^{13}\mathrm{C}$ hyperfine interactions, the symmetry has been revealed to be ${C}_{3v}$ with the arrangement of the four nearest-neighbor carbon atoms slightly distorted from a regular tetrahedron.