Experimental observations are reported of high-frequency currents associated with thin photoconducting cadmium sulphide platelets having flat and parallel faces. They appear under conditions when `round-trip gain' due to acousto-electric amplification is achieved. They are correlated with departures from Ohm's law. The results are confined to conditions under which a linear theory is believed applicable. The linear theory is outlined and comparison is made with a variety of experimental observations. Semiquantitative agreement is obtained.

https://iopscience.iop.org/article/10.1088/0022-3719/2/1/324/pdf

High-frequency acoustoelectric currents and departures from Ohm's law in thin platelets of CdS I. Linear behaviour

A review is given of a variety of physical effects in piezoelectric semiconductors originating in the relative strong coupling between the electronic and sound wave systems. Among the topics discussed are sound amplification, non-electronic losses, effects of free carrier trapping, and a number of strong non-linear effects as current saturation, current oscillations, and traveling high field and flux domains. A short discussion of some recent non-linear theories is also included.

Acoustoelectric Effects in Piezoelectric Semiconductors with main Emphasis on CdS and ZnO

Subharmonic generation of acoustic flux in GaAs

Gigahertz acousto-electric oscillations in zinc oxide

Results are presented for ZnO acoustoelectric oscillators at room temperature of resistivities from 100 Ω cm to 104 Ω cm. Pulsed operation as well as continuous wave operation was possible and frequencies up to 5 GHz and 4 GHz respectively were observed. The oscillations are divided into three different types depending on the thickness and the conductivity of the sample in question. The experimental results are compared with the existing theories for the acoustoelectric oscillator and with results previously obtained with CdS oscillators.

A room temperature ZnO acoustoelectric microwave oscillator

This letter describes some characteristics of an oscillator based upon the acoustoelectric interaction in piezoelectric semiconductors—the acoustoelectric oscillator. Particular reference is made to frequency modulation and to related-device applications.

J.D. Maines

Papers

Acoustoelectric u.h.f. oscillator: frequency modulation