X-ray diffraction and optical characterization of interdiffusion in self-assembled InAs/GaAs quantum-dot superlattices

We report on the characterization of thermally induced interdiffusion in In As/GaAs quantum-dot superlattices with high-resolution x-ray diffraction an d photoluminescence techniques. The dynamical theory is employed to simulat e the measured x-ray diffraction rocking curves of the InAs/GaAs quantum-do t superlattices annealed at different temperatures. Excellent agreement bet ween the experimental curves and the simulations is achieved when the compo sition, thickness, and stress variations caused by interdiffusion are taken in account. It is found that the significant In-Ga intermixing occurs even in the as-grown InAs/GaAs quantum dots. The diffusion coefficients at diff erent temperatures are estimated. (C) 2000 American Institute of Physics. [ S0003-6951(00)02440-2].