Growth of Ge nanoislands on Si (001) using molecular beam epitaxy

Self-assembled nano-sized Ge islands have been grown on Si (001) substrates using a solid source molecular beam epitaxy. Detailed island morphological studies at different deposition temperatures and flux rate of as-grown and annealed nanocrystals are reported. Both the alloy composition and in-plane strain in the grown islands have been determined from high-resolution XRD and Raman study. The shape and size of the grown islands and the coarsening mechanism are explicitly discussed with the help of data obtained from AFM topographic images. The current-voltage characteristics of a single isolated island exhibits Coulomb blockade behaviour at room temperature.