Ion-bombardment induced morphology change of device related SiGe multilayer heterostructures

Ion assisted molecular beam epitaxy bears the potential to tune morphological and structural parameters of semiconductor heterolayers for opto- and nanoelectronic applications. The morphology evolution and the degree of relaxation are influenced by the ion beam parameters and the strain of the heteroepitaxial film. In this work, the morphology of silicon germanium (SiGe) layers due to Si⁺-ion beam treatment during growth is investigated by atomic force microscopy (AFM) as a function of ion energy and ion flux density. Ion energies range from 100 eV to 1000 eV. The AFM measurements are used to determine the roughness distribution across the wafers. A regular pattern of SiGe crystallites is found, where the damage due to low ion energy Si⁺-ion bombardment is medium and the degree of relaxation, determined by Raman spectroscopy, is below 25%.