Mott transition from a diluted exciton gas to a dense electron-hole plasma in a single V-shaped quantum wire

We report on the study of many-body interactions in a single high-quality V-shaped quantum wire by means of continuous and time-resolved microphotoluminescence. The transition from a weakly interacting exciton gas when the carrier density n is less than 10 cm ~i.e., naX,0.1, with aX the exciton Bohr radius! to a dense electron-hole plasma (n.10 cm, i.e., naX.1) is systematically followed in the system as the carrier density is increased. We show that this transition occurs gradually: the free carriers first coexist with excitons for naX.0.1; then the electron-hole plasma becomes degenerate at naX50.8. We also show that the nonlinear effects are strongly related to the kind of disorder and localization properties in the structure especially in the low-density regime.