Evidence for interlayer donor-acceptor recombination in type IIGaAs/AlAs superlattices

Steady-state and time-resolved photoluminescence of (GaAs)(7)(AlAs)(9) type II superlattices grown simultaneously by molecular beam epitaxy on (311)A and (100) GaAs substrates, intentionally undoped or uniformly doped with si licon, has been studied. It is shown that at temperatures T > 30 K, the dom inant Line in the photoluminescence spectra of superlattices is caused by d onor-acceptor recombination between the donors located in the AlAs layers a nd the accepters in the GaAs layers. The sum of the binding energies of the donors and accepters in the pairs has been determined. A spectrally-depend ent linear polarization of the donor-acceptor line along the direction of t he interface corrrugation of the superlattice has been discovered in the sp ectra of (311)A-oriented superlattices. (C) 2000 Academic Press.