IMPURITY-INDUCED DISORDERING IN FRACTIONAL-LAYER GROWTH ON A (001) VICINAL SURFACE BY METALORGANIC CHEMICAL VAPOR-DEPOSITION

(AlAs)1/2(GaAs)1 /2 fractional-layer superlattices (FLSs) are grown on a (001) GaAs substrate, tilted slightly in the [1̄10] direction using metalorganic chemical vapor deposition. The periodic structures are analyzed by x-ray superlattice satellite diffraction. The results suggest that the step flow mode from monolayer step is a dominant crystal growth process. However, the satellite intensities drastically decrease under heavy Si impurity doping conditions (n>2×1017 cm-3), showing that impurity-induced disordering occurs during fractional-layer growth. The growth mechanism under impurity doping conditions is also discussed.