FREQUENCY-DEPENDENT ACOUSTOELECTRIC INTERACTION IN PROXIMITY-COUPLED PIEZOELECTRIC-SEMICONDUCTOR HYBRIDS

A quantitative analysis of the frequency-dependent acousto-electric in teraction between a high-mobility quasi-two dimensional electron syste m in a semiconductor heterostructure and a surface sound wave propagat ing on a piezoelectric crystal is presented. We show that for this hyb rid system a residual air gap between both partners strongly affects t he acousto-electric interaction. Frequency-dependent measurement of th e interaction enables us to determine the influence of the air gap on the strength of the interaction and the relevant parameters for the th eoretical description. Our analysis might be of importance for the des ign of future acousto-electric experiments but also devices where stro ng interaction between the sound wave and the low dimensional electron system is required. (C) 1997 Elsevier Science Ltd.