Acoustic Domains in Semiconducting CdS Revealed by Brillouin Scattering Measurements

Abstract

Acoustic domains in semiconducting CdS are studied by Brillouin scattering measurements at room temperature. Time-variations, spatial distributions and frequency spectra of the generated acoustic flux are revealed experimentally. The propagation of the acoustic flux is separated into regions of exponential growth, steady-state saturation and anomalous damping. Such flux behaviors are not accompanied by the corresponding change of the sample current. The frequency spectra range from 200 to 1200 MHz and change slightly during propagation. Linear acoustic gains in this frequency range agree fairly-well with the theoretical curve of White. However, the acoustoelectric phenomena cannot be explained by these low frequency acoustic waves only. Thus, Brillouin scattering is not always valid to examine the acoustoelectric instabilities because of its frequency limitation (\simeq2.8 GHz).