Surface Acoustic Waves in DC Fields

A SAW is excited on a side of a piezoelectric platelet (LiNbO₃) by an inter-digital transducer. The SAW propagating along the plane of lithium niobate is accompanied by a high-frequency electric field. This electric field penetrates into the 2D channel located in the semiconductor structure placed on the surface. The field produces electrical currents, which, in turn, cause Joule losses. As a result of the interaction of the SAW electric field with charge carriers, the SAW attenuation and its velocity shift are governed by the complex high-frequency conductivity, σ^hf(ω) . Therefore, the real and imaginary parts of the conductivity could be calculated from the SAW attenuation and velocity measured in the experiment. This “sandwich"-like experimental configuration enables contactless acoustoelectric experiments on non-piezoelectric 2D systems, for example built from Si and Ge.