Vanadium in CdTe: An electron-paramagnetic-resonance study

Abstract

The transition-metal ion vanadium in CdTe is studied using electron paramagnetic resonance (EPR) and photo-EPR. Based on the observation of central hyperfine interaction, the EPR measurements identify two vanadium related defects. They are assigned to ${\mathrm{V}}^{3+}$ and ${\mathrm{V}}^{2+}$, both substitutional for Cd. Whereas ${\mathrm{V}}^{3+}$ shows the classic isotropic EPR spectrum, the ${\mathrm{V}}^{2+}$ spectrum features triclinic symmetry caused by a strong Jahn-Teller coupling to both ${\ensuremath{\tau}}_{2}$ and $\ensuremath{\epsilon}$ vibronic modes. By means of photo-EPR the ${\mathrm{V}}^{2+}$/${\mathrm{V}}^{3+}$-donor level is determined at 0.67 eV below the conduction band.