  We explore the possibility of inducing in heterostructures driven by an ac
gate voltage the coherent current suppression recently found for nanoscale
conductors in oscillating fields. The destruction of current is fairly
independent of the transport voltage, but can be controlled by the driving
amplitude and frequency. Within a tight-binding approximation, we obtain
analytical results for the average current in the presence of driving. These
results are compared against an exact numerical treatment based on a
transfer-matrix approach.
