Formation of Two-Dimensional Si/Ge Nanostructures Observed by STM

Abstract

The growth of kinetically self-organized two-dimensional (2D) islands is described for Si/Si(111) epitaxy. The island size distribution for this system was measured using scanning tunneling microscopy (STM). The potential formation of thermodynamically stable strained islands of a specific size is discussed. The formation of 2D Si/Ge nanostructures at preexisting defects is studied. The step-flow growth mode is used to fabricate Si and Ge nanowires with a width of 3.5 nm and a thickness of one atomic layer (0.3 nm) by self-assembly. One atomic layer of Bi terminating the surface is used to distinguish between the elements Si and Ge. A difference in apparent height is measured in STM images for Si and Ge, respectively. Additionally, different kinds of 2D Si/Ge nanostructures, such as alternating Si and Ge nanorings having a width of 5–10 nm, were grown.