Atomic force microscopy studies of SiGe films and Si/SiGe heterostructures

Atomic force microscopy (AFM) is used to study the topography of strained SiGe films and multilayer Si/SiGe heterostructures. Strain relaxation processes are found to determine the formation of surface morphology, with distinct morphological features arising from both misfit dislocation formation and three-dimensional growth of coherent islands and pits on the surface. Studies of these features for various values of strain (Ge content) and growth temperature reveal the underlying physical processes determining the strain relaxation. Fourier analysis of AFM images is performed to obtain quantitative roughness information and to separate roughness components of different physical origin.