EXTREMELY FLAT INTERFACES IN GAAS ALGAAS QUANTUM-WELLS GROWN ON GAAS (411) A SUBSTRATES BY MOLECULAR-BEAM EPITAXY

GaAs/Al0.3Ga0.7As quantum wells (QWs) grown on (411)A-oriented GaAs su bstrates by molecular beam epitaxy (MBE) showed extremely flat interfa ces over a macroscopic area (about 200 mum phi) even for the case of n o growth interruption, which is mainly due to the intrinsically large migration of Ga atoms and layer growth in the step-flow mode on the (4 11)A plane. Photoluminescence linewidths at 4.2 K were almost the same as or better than the narrowest linewidths reported for GaAs/AlGaAs a nd GaAs/AlAs QWs grown on GaAs (100) substrates with growth interrupti on at each GaAs/AlGaAs(AlAs) interface. Only one sharp luminescence pe ak was observed for each QW on the (411)A substrates, in contrast with three luminescence peaks for the QWs on the (100) substrates, indicat ing that extremely flat and uniform interfaces over a macroscopic area of laser excitation (200 mum diameter) are realized in the GaAs/AlGaA s QWs grown on (411)A GaAs substrates.