Exciton front propagation in photoexcited GaAs quantum wells

Abstract

We report on the study of spatiotemporal self-organization of carriers in photoexcited GaAs quantum wells. Propagating interfaces between electron-rich and hole-rich regions are seen as expanding and collapsing exciton rings in exciton emission patterns. The interfaces preserve their integrity during expansion, remaining as sharp as in the steady state, which indicates that the dynamics is controlled by carrier transport. The front propagation velocity is measured and compared to theoretical model. The measurements of expanding and collapsing exciton rings afford a contactless method for probing the electron and hole transport.