Study on Efficiency of Piezoelectric Semiconductor SAW Convolver

SAW convolvers using piezoelectric semiconductors are studied theoretically and experimentally with emphasis on the feature that the polarization accompanied by the surface wave plays an important role in the determination of the distribution of the electric fields and the space charge in the piezoelectric semiconductor. The results of the analysis are the following. The operation of these convolvers are different from those of convolvers with a combined structure of a piezoelectric material and a semiconductor. Structures with layered conductivity distributions increase the open voltage by an order of magnitude and reduce the propagation loss. Methods to reduce the propagation loss are also discussed. The characteristics of convolvers using a photoconductive CdS crystal are in agreement with the theoretical results in general.