Ultrahigh-frequency surface acoustic waves for finite wave-vector spectroscopy of two-dimensional electrons

Ultrahigh-frequency (up to 24 GHz) surface acoustic waves were excited with short-period interdigital transducers and detected in GaAs/AlGaAs quantum wells with an optical scheme. We demonstrate that the transducers can be driven in a contactless fashion. Sets of two transducers permitted the coherent emission of surface acoustic waves and the creation of standing waves due to interference. The methods described offer bright prospects for finite wave-vector spectroscopy of two-dimensional electrons in a noninvasive way up to wave numbers of 10(6) cm(-1). (C) 2004 American Institute of Physics.