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(5) cm(-1) (i.e., na(X)<0.1, with a(X) the exciton Bohr radius) to a dense electron-hole plasma (n>10(6) cm(-1), i.e., na(X)>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 na(X)>0.1; then the electron-hole plasma becomes degenerate at na(X)=0.8. 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.