Depletion-Layer Transduction of Surface Waves on Piezoelectric Semiconductor

Effective generation and detection of surface elastic waves on semiconducting GaAs are achieved by using the depletion-layer which avoids the screening of piezoelectric fields by free carriers. A pair of interdigital transducers is constructed by evaporating Au on the (111) plane of GaAs, resulting in the formation of the Schottky barrier under the electrodes of the transducers. The surface wave of 25 MHz is propagated along the <110> direction. Applying the dc bias voltage to the Schottky barrier, the signal level is increased up to 30 dB. A fairly good agreement is obtained between an analysis and the experiments.