An investigation was made of interdiffusion and surface segregation in molecular beam epitaxially-grown stacked self-assembled quantum dots. High-resolution cross-sectional scanning tunnelling microscopy revealed lateral variations in the vertical positions of In atoms in both the wetting layers and dot stacks. In some regions, the wetting layer thickness was much less than the dot height. In other regions, the dot was immersed in the wetting layer. By using In and Ga atom counting, vertical In-Ga interdiffusion and 1/e segregation lengths of 1.25 and 2.8nm, respectively, were obtained. In the dot stacks, significant In-Ga intermixing was detected and was attributed mainly to In surface segregation.

Interdiffusion and Surface Segregation in Stacked Self-Assembled InAs/GaAs Quantum Dots B.Lita, R.S.Goldman, J.D.Phillips, P.K.Bhattacharya: Applied Physics Letters, 1999, 75[18], 2797-9