Thermalization effect on radiative decay of excitons in quantum wires

The radiative decay of one-dimensional (1D) excitons is studied in novel GaAs quantum wires (QWI's) prepared by molecular beam epitaxy. The temperature dependence of the radiative lifetime \ensuremath{\tau}(T) is measured, and is compared with that of 2D excitons in quantum wells (QW's): \ensuremath{\tau}(T) of 1D excitons grows much more slowly with T than that of 2D excitons, resulting in shorter lifetime for T>20 K. This is ascribed to thermalization in the concentrated 1D density of states in QWIs. Analysis based on a theory has revealed that \ensuremath{\tau}(T) is expressed as 92\ensuremath{\surd}T ps ${\mathrm{K}}^{\mathrm{\ensuremath{-}}1/2}$ in QWIs and as 24T ps ${\mathrm{K}}^{\mathrm{\ensuremath{-}}1}$ in QWs.