Indirect excitons in a potential energy landscape created by a   perforated electrode
  We report on the principle and realization of an excitonic device: a ramp that directs the transport of indirect excitons down a potential energy gradient created by a perforated electrode at constant voltage. The device provides an experimental proof of principle for controlling exciton transport with electrode density gradients. We observed that the exciton transport distance along the ramp increases with increasing exciton density. This effect is explained in terms of disorder screening by repulsive exciton-exciton interactions. 
C. J. Dorow, Y. Y. Kuznetsova, J. R. Leonard, M. K. Chu, L. V. Butov,   J. Wilkes, M. Hanson, and A. C. Gossard
cond-mat.mes-hall