Exciton Formation and Relaxation Dynamics in Quantum Wires

The dynamics of one-dimensional (1D) excitons is investigated in a GaAs/AlAs quantum wire array (QWR-A) using picosecond time resolved photoluminescence (PL) measurements. The excitation density is $4\times {10}^4\mathrm{cm}{}^{-1\mathrm{}}$, a factor of 20 below the Mott density. The rise and decay time constants of the excitonic PL in the QWR-A are 55 and 450 psec, respectively. The exciton formation time in 1D is determined to be $\approx 30\mathrm{psec}$. Our results suggest that exciton-acoustic-phonon scattering is enhanced in 1D. However, the rates of exciton scattering with carriers and excitons is reduced.