Optical Probing of Acoustic Flux Associated with Moving High-Field Domains in Semiconducting CdS Crystals

Abstract

The shape and time‐evolution characteristics of strong acoustic flux associated with moving acousto‐electric high‐field domains were investigated by means of a photoelastic method. The optical measuringsystem enabled us to determine the shape of the acoustic flux and to obtain quantitative data on its intensity. The width of the acoustic flux was measured to be ranging from 100 μ to several hundred microns, and the flux was found to be lagging behind the high‐field domain by several tens of microns. The acoustic flux grew with transit of the high‐field domain and tended to saturation. The peak shear stress near saturation was measured above 103 N/cm2, which was sufficient to produce mechanical fracture of the crystals. In many crystals the acoustic fluxes often assumed complicated structures consisting of several peaks. The succeeding peaks grew much faster than the preceding peak. It was shown that the succeeding peaks mainly consisted of lower‐frequency acoustic waves compared to the first peak. The experimental results were compared with the results of the computer simulation based on a simple model. Fairly good agreement was found in such characteristics as the formation and relative positions of the acoustic flux and the high‐field domain.