Arsenic precipitates in Al_0.3Ga_0.7As/GaAs multiple superlattice and quantum well structures

Abstract

Arsenic precipitates in Al0.3Ga0.7As/GaAs multiple superlattices and quantum well structures which were grown at low substrate temperatures by molecular beam epitaxy were studied by transmission electron microscopy. Novel precipitate microstructures were observed in annealed samples, including confinement of precipitates in GaAs wells and nearly complete depletion of precipitates in a short period superlattice. It is shown that these observed microstructures can be explained as a result of the difference of precipitate/matrix interfacial energies in GaAs and Al0.3Ga 0.7As.