Phonon scattering by Cr ions in GaAs

Abstract
Measurements of the thermal conductivity of 13 samples of Cr-doped GaAs within the range of 50 mK to 250K show the presence of strong resonant phonon scattering. Resonances at 21, 80, 150, 400 and 690 GHz which only occur in semi-insulating and p-type samples are attributed to substitutional Cr3+, which appears to be very strongly coupled to the lattice, and a possible level scheme is proposed. Scattering at 2+. Since this could not occur in the static Jahn-Teller limit it provides support for a dynamic model and the data are in agreement with calculations by Abhvani et al. (1981) if the tunnelling parameter delta 13+ concentration in GaAs samples.