Efficient ZnO-SiO2-Si Sezawa Wave Convolver

Abstract

A detailed design theory of the Sezawa wave convolver is developed, and the fabrication of a high-efficiency convolver using a ZnO-Si0,-Si structure is discussed. The important points to improve the efficiency are 1) an optimum choice of SAW propagation direction on the Si substrate, 2) an optimum design of the resistivily of the Si epitaxial layer and ZnO film thickness, and 3) an improvement for low- ering SAW propagation lsos and resistance of output circuit. The ex- periments were carried out for two specifications each with a 20-mm and 40-mm gate length. The highest efficiency (F,) of -35 dBm was obtained in the gate length of 20 mm while the time-bandwidth product (ET) was 107. The highest ET product of 227 was obtained in the gate length of 40 mm, while F, was -47.5 dBm. At the present time, the maximum available ETproduct is less than 320 due to the group velocity dispersion.