Structural characteristics of self-assembled-Ge/Si quantum dot superlattices

In this paper, the interface structural parameters, mainly roughness and the interdiffusion properties have been investigated in two series of Ge/Si quantum dot superlattices (QDSLs), grown by solid-source molecular beam epitaxy (MBE) on Si (100) substrate with S-K mode at 540 degrees C When the nominal thickness of Ge layer increased from 1.2 to 1.8 nm, the Ge layers get rough and the thickness of Ge layers decreases. With the periods of Ge/Si QDSLs increase, the thicknesses of Ge wetting layers (WLs) tend to be thinner and the roughness of Ge dots' height becomes larger. The composition of the quantum dots (QDs) is also estimated by the integrated peak intensity ratio IGe-Ge/ISi-Ge from Raman spectra. The calculated result of Ge/Si interdiffusion from Raman spectra is in accordance with the analyses results of X-ray Reflection (XRR) experiments.