Acoustoelectric amplification in composite piezoelectric and semiconducting structures

Acoustoelectric amplification in composite semiconducting and piezoelectric structures is discussed, with emphasis on work with guided plate modes in PZT and LiNbO3. These guided modes have proven to yield very strong amplification at frequencies between 1 and 10 MHz, with a variety of mode-dependent characteristics such as frequency dependence and dispersion. A simple theoretical treatment for the acoustoelectric interaction in composite structures is given, which stresses the analogy with a piezoelectric semiconductor. The behavior expected from an interaction with several types of carriers is considered, and it is shown that the shape of the amplification curve, in this case, depends on an average drift parameter. Some experimental results involving both electrons and holes are also cited.