  In traditional approaches of obtaining quantized acoustoelectric current, a
narrow channel is fabricated to form quantum dots, which hold a fixed number of
electrons at a certain depth. We propose a natural way of forming quantum dots
without the narrow channel, by the interference of two surface acoustic waves
(SAWs) propagating across each other. A wide transportation area is defined by
the usual (but widely separated) split-gate structure with another independent
gate in between. This design can increase the quantized current by one to two
orders of magnitude. The three-gate structure also allows separate control of
the barrier height and the side-gate pinch-off voltage, thus avoids current
leakage through the area beneath the side gates.
