Interdiffusion between GaAs and AlAs

Epitaxial structures composed of thin layers of GaAs and AlAs were grown by the technique of molecular beam epitaxy. The interdiffusion coefficient was measured by Auger-electron profiling after annealing the structures under As-rich conditions over the temperature range 850–1100 °C. This coefficient was found to be extremely small, in the 10−18 cm2/sec region at the lower temperatures. It also depends on the alloy composition, decreasing with an increase in Al. Such dependence becomes stronger at higher temperatures, giving rise to activation energies of 4.3 and 3.6 eV in the limits of GaAs and AlAs, respectively.