Acoustoelectric Amplification in Lateral-Extensional Composite Piezo-Silicon Resonant Cavities

In this work, evidence for acoustoelectric (AE) amplification in lateral-extensional thin-film piezoelectric-on-silicon (TPoS) resonant cavities for the first time is demonstrated. Due to the piezoelectric coupling, an evanescent electromagnetic wave is induced in the silicon (Si) layer that is a part of the resonant cavity, exchanging momentum with the carriers. Therefore, by injecting an electric current in this layer, the acoustic equivalent of Cherenkov radiation - AE amplification - can be realized. Such phenomenon is observed in a 1 GHz TPoS resonant cavity in which lateral field excitation is utilized to excite the acoustic wave.