Abstract

We have performed exciton transport measurements over large distances in ultrapure Cu₂O samples. For the local, time-resolved detection of the particles several millimeters away from the initial excitation spot, we record the photovoltaic current resulting from exciton dissociation at a semiconductor-metal interface. This method of detection is appropriate for optically inactive excitons, such as paraexcitons in Cu₂O. The results bring evidence for the sudden appearance of an anomalous particle current above a critical particle density and below a critical temperature. We attribute this effect to the onset of an excitonic superfluid phase.

© 1993 Optical Society of America