ALGAAS GAAS AND INGAAS/GAAS QUANTUM-WELLS GROWN ON GAAS (111)A SUBSTRATES/

We have sown AlGaAs/GaAs and InGaAs/GaAs single quantum wells (SQWs) o n exactly-oriented and misoriented GaAs (111)A substrates by molecular beam epitaxy (MBE). The photoluminescence (PL) spectra of AlGaAs/GaAs SQWs grown on (111)A and related substrates depend on misorientation angles. Under optimized growth conditions, SQWs grown on the exactly-o riented and 5 degrees-misoriented substrates show good surface morphol ogy and have less than one monolayer of heterointerface roughness. On the other hand, 3 degrees-misoriented samples show numerous giant terr aces on the surface and their PL spectra show red-shifted and broadene d peaks. We show that this phenomenon is caused by Al content and GaAs well thickness modulation at the risers of giant terraces. We have al so observed Al content reduction in facets that occur spontaneously on AlGaAs layers grown on the exactly-oriented (111)A.