Frequency-dependent acousto-electric interaction in proximity-coupled piezoelectric-semiconductor hybrids

A quantitative analysis of the frequency-dependent acousto-electric interaction between a high-mobility quasi-two dimensional electron system in a semiconductor heterostructure and a surface sound wave propagating on a piezoelectric crystal is presented. We show that for this hybrid system a residual air gap between both partners strongly affects the acousto-electric interaction. Frequency-dependent measurement of the interaction enables us to determine the influence of the air gap on the strength of the interaction and the relevant parameters for the theoretical description. Our analysis might be of importance for the design of future acousto-electric experiments but also devices where strong interaction between the sound wave and the low dimensional electron system is required.