Acoustoelectric interaction in semiconductors

A family of novel devices for electronic imaging is described and several different realizations age presented. Direct electronic Fourier transform (DEFT) cameras employ coupling between surface strain waves, the image intensity, and electrical charge to produce electronic signals representing the spatial Fourier transform of the image at a single pair of terminals. This signal can be easily processed to accomplish pattern recognition, all-electronic image magnification (zoom) and stabilization, motion detection, and focusing. Reproduction of the image is expected to be accomplished by a light valve employing strain-induced modulation of uniform light. Experimental results for light intensity variation in one dimension are reviewed for a silicon chip bulk acoustic wave camera and for a CdS surface wave camera. Some preliminary results are also reported for a fused quartz elastobirefringent light valve image reconstruction device.

http://ieeexplore.ieee.org/iel5/5/31183/01451501.pdf

DEFT: Direct electronic Fourier transforms of optical images

The addition of active, nonlinear, and nonreciprocal functionalities to passive piezoelectric acoustic wave technologies could enable all-acoustic and therefore ultra-compact radiofrequency signal processors. Toward this goal, we present a heterogeneously integrated acoustoelectric material platform consisting of a 50 nm indium gallium arsenide epitaxial semiconductor film in direct contact with a 41° YX lithium niobate piezoelectric substrate. We then demonstrate three of the main components of an all-acoustic radiofrequency signal processor: passive delay line filters, amplifiers, and circulators. Heterogeneous integration allows for simultaneous, independent optimization of the piezoelectric-acoustic and electronic properties, leading to the highest performing surface acoustic wave amplifiers ever developed in terms of gain per unit length and DC power dissipation, as well as the first-ever demonstrated acoustoelectric circulator with an isolation of 46 dB with a pulsed DC bias. Finally, we describe how the remaining components of an all-acoustic radiofrequency signal processor are an extension of this work. Radio frequency signal processing (RFSP) currently involves a mix of components with differing operation principles, which hinders miniaturisation. Here, Hackett et al. succeed in creating acoustic non-reciprocal circulators, amplifiers, and passive filters, paving the way for all acoustic single-chip RFSP.

/pdf/towards-single-chip-radiofrequency-signal-processing-via-lusx0kph8f.pdf

Towards single-chip radiofrequency signal processing via acoustoelectric electron-phonon interactions.

Acoustoelectronics is based both in its conceptional and experimental aspects on the piezoelectric effect discovered by J. Curie and P. Curie. This paper reviews the research on acoustoelectronics which has been carried out at A. F. loffe Physico-Technical Institute in Leningrad. Three basic types of acoustoelectron interactions are considered: (i) interaction of bulk acoustic waves in a piezoelectric semiconductor with free charge carriers; (ii) interaction of surface acoustic waves in a piezodielectric crystal with free carriers in an adjacent semiconductor and (iii) interaction of surface acoustic waves in a piezoelectric crystal with free electrons in vacuum. The main characteristic features of the acoustoelectron interactions are illustrated by the experimental results obtained with well known piezoelectric crystals such as CdS, Te, InSb, SiO2, LiNbO3. Both linear and nonlinear acoustoelectron effects are described.

E. M. Conwell

Papers

Mixing of Acoustic Waves in Piezoelectric Semiconductors