As4 pressure dependence of the interface flatness of GaAsAl0.3Ga0.7As quantum wells grown on (411) A GaAs substrates by MBE

Arsenic pressure dependence of the interface flatness of GaAsAlGaAs (Al content of 0.27-0.29) quantum wells (QWs) grown on (411)A GaAs substrates by molecular beam epitaxy (MBE) was investigated. Effectively atomically flat (411)A interfaces could be realized under a low VIII ratio (VIII = 7), but the interfaces decreased in flatness under an increased VIII ratio (VIII ≥ 11). The linewidth of the photoluminescence peak increases with increasing the VIII radio during the growth of the GaAs QW layers, but does not increase so much with increasing VIII ratio during the growth of the AlGaAs barrier layers, indicating that the flatness of an AlGaAsGaAs upper interface of the GaAs QWs grown on (411)A substrates is more strongly affected by the high VIII ratio than that of a GaAsAlGaAs lower interface of the GaAs QWs. The excess fluctuation in the GaAs well width (ΔLw) which results from the roughness of the upper interface caused by the high VIII ratio increases parabolically as a function of the GaAs well width (Lwo). This result was explained in terms of the formation of microsteps consisting of (311)A and (511)A microfacets on the averaged (411)A GaAs surface. Sizes of the (311)A and (511)A microfacets increase in proportion with the GaAs well width (Lwo).