PSEUDODIRECT BIEXCITONS IN GAAS ALAS TYPE-II SUPERLATTICES/

We report on the biexciton formation of the pseudodirect exciton consi sting of the AlAs-X(z) electron and the GaAs-Gamma heavy hole in (GaAs )(m)/(AlAs)(m) type-II superlattices with m = 10, 12, and 13 monolayer s. The photoluminescence lineshape of the pseudodirect exciton exhibit s a doublet feature having an energy separation of similar to 3 meV at the excitation power of the order of mW/cm(2) in all the samples, and the low-energy band grows superlinearly. The transient profiles of th e doublet photoluminescence band early indicate the biexciton formatio n: the delay of the rise of the biexciton photoluminescence on the low -energy side and its shorter decay time in comparison with the exciton photoluminescence.