Acoustic waves and semiconductors

In this talk the emphasis will be on the recent work that has been done to exploit the coupling between traveling acoustic waves and drifting electrons. Three systems will be included: (1) volume shear waves; (2) surface Rayleigh waves; and (3) surface Bleustein waves. The linear amplification that results from this coupling is more than sufficient to overcome the intrinsic loss of the crystal lattice and the insertion loss of the transducers. The utility of all this will be illustrated with a description of a new delay line which provides a delay of 20 milliseconds with zero insertion loss for frequencies near 100 MHz.