TIME-RESOLVED SPECTROSCOPY OF SINGLE QUANTUM DOTS - FERMI GAS OF EXCITONS

Photoluminescence measurements with spatial and temporal resolution ar e performed on individual GaAs/GaAlAs quantum dots. Already 10 ps afte r weak, resonant excitation, we observe luminescence which evolves to a spectrum of distinct, narrow lines. With increasing excitation inten sity, the spectral weight shifts from the lowest to higher levels but the peak energies hardly change. Our results demonstrate that Coulomb scattering is an important relaxation mechanism and suggest that the i nteracting electron-hole plasma in quantum dots behaves like an excito n gas obeying Pauli exclusion.