Thermal stability of GaAs/InAs/GaAs heterostructure studied by x-ray crystal truncation rod scattering measurement

The distribution of In in a GaAs/InAs(1 monolayer)/GaAs structure was investigated by X-ray crystal truncation rod scattering measurement. The InAs layer and the GaAs cap layer were grown at 480degreesC on the GaAs buffer layer grown at 590degreesC. After the growth, the samples were annealed at different temperatures, and the thermal stability of the GaAs/InAs/GaAs structure was investigated. In atoms were surely confined in 1 ML(monolayer) when the sample was as grown. However, when the sample was annealed at 590degreesC only for 10 min, the In atoms widely spread in the GaAs layers. The diffusion coefficient of In in the GaAs layer grown at 480degreesC was larger than that in the GaAs layer grown at 590degreesC. The difference is considered to be caused by the Ga vacancies generated in the GaAs layer grown at 480degreesC.