6533b85bfe1ef96bd12bb335

RESEARCH PRODUCT

Pumping of single electrons with a traveling wave

subject

description

Abstract We describe the operation and performance of a one-dimensional chain of small metallic islands whose potentials are modulated in a wave-like manner. The sinusoidal voltages, applied to the gate electrodes, carry individual charges coherently through the array. In practice, the wave-like potential is induced on the gates by a surface acoustic wave (SAW) traveling on a piezoelectric substrate. The resulting transfer of charges should produce a DC current I = ± ef through the chain, where f is the frequency of the wave and the sign ofthe current depends on the value of the common DC bias of the islands as well as on the direction of the wave propagation. We observe, however, a much smaller current than expected and investigate the factors affecting the fundamental relation between the current and frequency. We demonstrate that the most harmful factor in practice is an uncompensated background charge of random nature, which usually exists in substrates and oxide barriers.