Interface roughness and period variations in the AlGaAs system grown by molecular beam epitaxy

Abstract
The interface extent on a large range of Al0.35Ga0.65As/GaAs and AlAs/GaAs multiple quantum well structures has been obtained by X-ray diffraction. The average interface extent perpendicular to the growth direction from GaAs to Al0.35Ga0.65As or AlAs is of the order of 3.8 monolayers, whereas the 'inverted' or opposite interface for both structures is broader: 4.9 monolayers for AlAs to GaAs and 5.6 monolayers for Al0.35Ga0.65As to GaAs. These interface extents represent significant intermixing on only a few monolayers. The sensitivity and the reproducibility of these results is discussed.