Ultrasonic Attenuation in Gallium-Arsenide Single Crystals.

The temperature and frequency dependences of the velocity and the attenuation coefficient, (alpha), of both longitudinal and shear ultrasonic waves, propagating in the {100}, {110}, and {111} directions of GaAs single crystals, have been measured by means of the pulse-echo technique. The temperature range investigated was 110 K to 240 K for shear waves and 110 K to 300 K for longitudinal waves. The frequencies used were in the range of 45 to 170 MHz. In the temperature region investigated, it was found that the dependence of (alpha) on the angular frequency (omega) was of the form (alpha) (PROPORTIONAL) (omega)('n), with n = 2 (+OR-) 0.2 for longitudinal waves and 1.7 (+OR-) 0.1 for shear waves. By fitting our attenuation data to the theory given by Nava et al., the temperature dependences of the effective ultrasonic Gruneissen parameters normalized to appropriate temperatures have also been determined.