Magnetic circular dichroism and site-selective optically detected magnetic resonance of the deep amphoteric vanadium impurity in 6H-SiC

Abstract

Magnetic-circular-dichroism (MCD) absorption and optically detected electron-spin-resonance (ESR) data for the neutral vanadium impurity, ${\mathrm{V}}^{4+}$(3${\mathit{d}}^{1}$) on the \ensuremath{\alpha}, \ensuremath{\beta}, and \ensuremath{\gamma} sites in 6H-SiC are presented and supplemented by linearly polarized absorption and luminescence spectra. An analysis of the linearly polarized spectra yields crystal-field-level schemes in zero magnetic field and an intensity parameter u for ${\mathrm{V}}^{4+}$ on each of the three Si sites. This information is used to account for the ${\mathrm{V}}^{4+}$ MCD zero-phonon-line positions, signs, and relative intensities without an adjustable parameter. Evidence of Jahn-Teller effects is found in both the ${\mathrm{V}}^{4+}$ $^{2}$E ground and the $^{2}$${\mathit{T}}_{2}$ excited states. The MCD-ESR technique, in the present case, is site selective. The ${\mathrm{V}}^{4+}$ resonances associated with the \ensuremath{\beta} and the \ensuremath{\gamma} site are virtually identical and cannot be distinguished by conventional ESR. The g factors for all three sites are satisfactorily explained within the framework of crystal-field theory.