Transient four-wave mixing in T-shaped GaAs quantum wires

The binding energy of excitons and biexcitons and the exciton dephasing in T-shaped GaAs quantum wires is investigated by transient four-wave mixing. The T-shaped structure is fabricated by cleaved-edge overgrowth, and its ge ometry is engineered to optimize the one-dimensional confinement. In this w ire of 6.6 x 24 nm(2) size, we find a one-dimensional confinement of more t han 20 meV, an inhomogeneous broadening of 3.4 meV, an exciton binding ener gy of 12 meV, and a biexciton binding energy of 2.0 meV. A dispersion of th e homogeneous linewidth within the inhomogeneous broadening due to phonon-a ssisted relaxation is observed. The exciton acoustic-phonon-scattering coef ficient of 6.1 +/- 0.5 mu eV/K is larger than in comparable quantum-well st ructures. [S0163-1829(99)04147-8].