SiGe nanostructures

The growth modes of Ge on Si (111) and (100) was compared, in order to create the possibility of self-organized patterns of scalable periodicity and amplitude. Patterns induced by kinetic-stress-driven instability, which develops during the growth of Si(100), were also evidenced. In order to understand the nucleation of coherent islands inside the pits, the total energy E of coherent islands on both substrate types was calculated with respect to a continuous film using the relation E = ERV + ESS, where ER is the relaxation energy per unit volume, ES the change in the system surface energy due to island formation, V the total island volume and S the change in exposed surface with respect to the flat surface. Various lithographic techniques which have been proposed for the nanopatterning of Si substrates, were also used. It was concluded that the initial volume of Ge in the pit is already partially relaxed and that the Ge has a lower elastic energy than if it was formed on a flat surface.