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

Abstract

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 geometry is engineered to optimize the one-dimensional confinement. In this wire of $6.6\ifmmode\times\else\texttimes\fi{}24 {\mathrm{nm}}^{2}$ size, we find a one-dimensional confinement of more than 20 meV, an inhomogeneous broadening of 3.4 meV, an exciton binding energy of 12 meV, and a biexciton binding energy of 2.0 meV. A dispersion of the homogeneous linewidth within the inhomogeneous broadening due to phonon-assisted relaxation is observed. The exciton acoustic-phonon-scattering coefficient of $6.1\ifmmode\pm\else\textpm\fi{}0.5 \ensuremath{\mu}\mathrm{e}\mathrm{V}/\mathrm{K}$ is larger than in comparable quantum-well structures.