Monolayer islands in an interrupted-growth type-II single quantum well

We have observed splittings in the luminescence and excitation spectra of a GaAs/AlAs type-II single quantum well with growth interruption at the interfaces. The splittings indicate the formation of large monolayer-smooth islands with a lateral extent much larger than the type-II indirect-exciton Bohr radius. Evidence for exciton diffusion between islands on a microsecond time scale is also presented.