As 4 pressure dependence of the interface flatness of [formula omitted] quantum wells grown on (411) A GaAs substrates by MBE

Abstract

Arsenic pressure dependence of the interface flatness of GaAs AlGaAs (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 V III ratio ( V III = 7 ), but the interfaces decreased in flatness under an increased V III ratio ( V III ≥ 11 ). The linewidth of the photoluminescence peak increases with increasing the V III radio during the growth of the GaAs QW layers, but does not increase so much with increasing V III ratio during the growth of the AlGaAs barrier layers, indicating that the flatness of an AlGaAs GaAs upper interface of the GaAs QWs grown on (411)A substrates is more strongly affected by the high V III ratio than that of a GaAs AlGaAs lower interface of the GaAs QWs. The excess fluctuation in the GaAs well width ( ΔL w) which results from the roughness of the upper interface caused by the high V III ratio increases parabolically as a function of the GaAs well width ( L wo). 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 ( L wo).