Brillouin Scattering Studies of Acoustoelectric Domain Formation in Semiconducting CdS

The growth of the flux intensity in acoustoelectric domains in semiconducting CdS has been followed over five orders of magnitude for frequencies between 0.2 and 5 GHz using the Brillouin scattering technique. The form of the flux domains is exponential on both sides with a halfwidth of about 300 μm. By studying their formation in the very early stage before the current decay, it was found that the frequencies and amplification factors of the flux appearing first are close to those predicted by the linear theory. After the current has started to decay, higher and lower frequencies are observed, the lower with much higher amplification and intensities. It seems that the electric field inside the domain does not have an essential influence on the flux growth. The experimental results are compared with some acoustoelectric amplification models.