FORMATION AND CHARACTERIZATION OF GAAS AS SUPERLATTICE GROWN BY MOLECULAR-BEAM EPITAXY AT LOW SUBSTRATE-TEMPERATURE/

High-resolution X-ray diffractometer and transmission electron microsc ope (TEM) are used to characterize the redistribution of As precipitat es in Si delta-doped GaAs grown by molecular beam epitaxy at low subst rate temperature (230 degrees C). The superlattice satellite peaks are observed for samples annealed at 700-800 degrees C for 10 min, which is attributed to the formation of a GaAs/As superlattice during the an nealing period. The degree of As precipitates confined on the delta-do ped planes is revealed on the intensity of satellite peaks in the X-ra y rocking curves, as confirmed by the TEM observations. The lattice ex pansion and contraction of the annealed low-temperature epitaxial laye rs can be easily observed from the asymmetry of the satellite peaks.