ABSTRACT
The defect structure and the mechanisms ofheterointerfacial diffusion upon annealing of AlAs/GaAs:Be multiple quantum wells grown under low temperature conditions are investigated by high-resolution transmission electron microscopy. Numerical data on the local layer stoichiometry across the heterointerfaces obtained by the quantitative analysis of micrographs recorded under chemically sensitive imaging conditions are used to calculate diffusion parameters controlling the exchange of aluminium and gallium atoms dependent on the beryllium doping concentration. It is demonstrated that the thermal stability of AlAs/GaAs:Be multiple quantum wells against heterointerfacial mixing as well as against the formation of arsenic precipitates is significantly improved compared to undoped material when layers are grown in the high dopant regime and are subjected to moderate anneals.
