QUANTIZED CURRENT IN ONE-DIMENSIONAL CHANNEL INDUCED BY SURFACE ACOUSTIC-WAVES

We report an observation of the quantized acoustoelectric current indu ced by surface acoustic wave with frequency f approximate to 3 GHz thr ough a 1D channel defined in a GaAs-AlGaAs heterostructure by a split gate. When the split gate is pinched off the acoustoelectric current c an be observed only for sufficiently high RF power levels, consistent with electrons being forced through the channel by the surface acousti c wave. As gate voltage is made less negative the current shows quanti zed steps in units I = e.f where e is the electron charge. The current on the first plateau coincides with the calculated value I = e.f with the accuracy limited by the error (0.3 %) of our measuring instrument . The current value at the plateau was found to be stable over an inte rval of source-drain voltages and temperatures up to 4 K. The observed quantization is due to trapping of electrons in the moving potential minima, with the number of electrons in each minimum controlled by ele ctron-electron repulsion. The accuracy of the current quantization obs erved in our experiments suggests that SAW devices may open a new rout e towards the creation of a current standard. Different possible desig ns of SAW based current standard are discussed. (C) 1998 Elsevier Scie nce B.V. All rights reserved.