Nanodot to nanowire: A strain-driven shape transition in self-organized endotaxial CoSi2 on Si(100)

We report a phenomenon of strain-driven shape transition in the growth of nanoscale self-organized endotaxial CoSi2 islands on Si(100) substrates. Nanodots of CoSi2 grow in the square shape following the four fold symmetry of the Si(100) substrate, up to a critical size of 67 × 67 nm2, where a shape transition takes place. Larger islands grow as nanowires with ever increasing length and the width decreasing to an asymptotic value of ∼25 nm. This produces long nanowires of nearly constant width. The endotaxial nanostructures grow into the Si substrate with a small extension above the surface.