Surface state memory in surface acoustoelectric correlator

Abstract

We show that surface acoustic signals can be stored in and read from electron traps at the surface of a semiconductor that is adjacent to the piezoelectric on which the surface wave propagates. The observed memory action is explained by the large‐signal dynamics of the charging and discharging of the traps near a slightly depleted surface. The storage of the signal is accomplished by creating a zero‐frequency k pattern which fills the traps. The reading of the signal can be done by either correlation or convolution with another surface acoustic signal. This correlation device with internal memory does not require precise signal timing, operates with all signals at the same frequency, and does not require external time inversion of the reference signal.