Step-bunching and strain effects in Si1-xGex layers and superlattices on vicinal Si(001)

A comparative study is reported of kinetically and thermodynamically driven growth instabilities in the Si SiGe heterosystem on vicinal Si(001). Investigating single Si1-xGex-layers and Si1-xGexSi superlattices, a wide range of the relevant growth parameter space is mapped out, In contrast to earlier reports no evidence for strian-induced step-bunching is found, Single Si1-xGex layers replicate the morphology of the underlying buffer layers and tend to form but clusters near thermal equilibrium. In Si1-xGex/Si superlattices. no significant influence of the Ge-related strain on the step-bunching morphology can be seen. On the other hand, the effect of growth temperature is very pronounced. again indicating the dominant role of kinetics in the fort-nation of step-bunches. (C) 2002 Elsevier Science B.V. All rights reserved.