Acoustic paramagnetic resonance of vanadium in semi-insulating GaAs

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Abstract
The authors report strong acoustic paramagnetic resonances (APR) from LEC-grown semi-insulating GaAs:V. The results obtained are consistent with observations made on similar samples by other workers using thermally detected electron paramagnetic resonance (TDEPR). The results can be interpreted as being due to a V2+-X centre producing phonon scattering where X is some other lattice defect or impurity associated with the vanadium. In one sample the APR is only observed after illumination of the sample while another sample that contained fewer impurities apart from vanadium showed the APR in the dark and enhancement after illumination. They suggest that illumination converts V3+-X centres into V2+-X by capturing an excited electron in the former case whereas in the second case illumination converts V+-X centres into V2+-X centres and the electron released is trapped at another site with a very long life at low temperature.