Ultrasonic studies of n-Ge sample by buffer-rod

In this paper, we used a nondestructive method with ultrasounds to measure acoustic and spectral parameters for two Ge samples, one doped with As and another one pure. We examined the variation of the ultrasound attenuation and velocity, under te influence of temperature and frequency which characterize the mechanical properties of the semiconductor sample material, such as elastic constants C-ij, transversal modules G(111) and G(100), the anisotropy factor A and the nonlinearity parameter beta. We give one empirical relation vs. the adiabatic approximation for the elastic constants. Our results are in agreement with the modern theory of crystal lattices elaborated by Leibfriend and Ludwig, which give a general relationship between the elastic constants and the temperature considering the anharmonic nature of the atomic oscillations. Measurements were made using two successive echoes and for each measurement point, the saved information consists of the amplitude and velocity determined from the reflected RF signal by the USIS program. We used the temperature range from 273 K to 873 K and the frequency domain from 2 MHz to 20 MHz, using Nortec and Krautkramer transducers. Probing at high temperatures was made possible using an AI buffer-rod interposed between the transducer and the sample. The experimental measurements were made using an ultrasonic device Sonic 136 Ultra made by Staveley Corporation.