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 τ(T) is measured, and is compared with that of 2D excitons in quantum wells (QW’s): τ(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 τ(T) is expressed as 92√T ps ${\mathrm{K}}^{\mathrm{-}1/2}$ in QWIs and as 24T ps ${\mathrm{K}}^{\mathrm{-}1}$ in QWs.