One-dimensional lateral growth of epitaxial islands on focused ion beam patterned substrates

Lateral growth of highly elongated SiGe islands in one dimension has been achieved by ex-situ substrate patterning using a focused ion beam (FIB) to create an array of surface grooves in the Si substrate. Growth of Si _0.7Ge_0.3 on this template results in preferential formation of strain-relieving islands next to the edges of the grooves under kinetically limited growth conditions. The length of the nanowire-like islands is limited only by the length of the patterned trench. Occasional bridging across the groove is also observed due to non-uniformity of the underlying topography and the strong preference for the formation of four-fold island structures in this system. The success of this method is dependent upon the initial Si buffer layer thickness and on the orientation of the grooves, which must be parallel to the crystallographic 〈110〉 directions. These results demonstrate that important crystallographic as well as kinetic factors must be considered for controlling the lateral growth of nanostructures on patterned substrates.