Single-electron acoustic charge transport by two counterpropagating surface acoustic wave beams

A powerful surface acoustic wave can transport charge along a quasi-one-dimensional channel defined in a piezoelectric semiconductor in packets confined to the minima of the wave's electrostatic potential. The interaction between electrons can suppress fluctuation in the number of electrons in a packet, resulting in a current that is proportional to the surface acoustic wave (SAW) frequency. This effect has been observed experimentally and is presently being considered as a possible route towards a standard of electric current. Here we present further study of this acoustic charge transport. The main finding is that a weak counterpropagating SAW beam can be used to improve the precision of the current delivered by the device. [S0163-1829(99)02431-5].