Formation of Self-Assembled Quantum Wires during Epitaxial Growth of Strained GeSn Alloys on Ge(100): Trench Excavation by Migrating Sn Islands

A pattern of trenches and wires oriented along $〈100〉$ directions was formed during epitaxial growth of GeSn alloys on Ge(100). The trenches appear as self-avoiding random walks at low densities and become organized into domains at higher densities. These patterns are believed to be caused by the migration of Sn islands on the surface, induced by diffusion of Ge from one side of the Sn island to the other. This morphological evolution is thought to be a kinetic pathway for phase separation of strained thin films and may be utilized for high-throughput creation of nanoscale patterns.