Inelastic neutron scattering by TA phonons in heavily doped gallium arsenide

The temperature dependence of the shape of the inelastic neutron scattering peak from TA phonons in GaAs heavily doped by Te was studied within the temperature interval from 363 to 253 K. It was shown that doping with tellurium (to a carrier concentration Ne ≈ 2 × 1018 cm−3) gives rise to the appearance of an additional contribution to neutron scattering on the high-energy side of the TA phonon resonances at values of the reduced wave vector q < 0.1a*. Below 320 K, the intensity of this additional component rises sharply, and then, below 273 K, the main TA peak and the additional shoulder merge almost completely. This additional scattering is believed to be due to a defect-induced mode, which may be responsible for the observed anomalies in the physical properties in this crystal.