Formation of Ge dots on Si(100) using reaction of Ge with sub-monolayer carbon on top

To form small and dense Ge dots, an availability of simple bottom-up method by using reaction of Ge and carbon (C) formed on Si(100) at low temperature through post-annealing has been investigated. Ge dots were formed at annealing temperature (TA) above 450 °C. Small, dense and relatively uniform dots were formed for Ge=7.5 MLs and C=0.05-0.1 ML at TA=650 °C. From the dependence of dot size and density on Ge thickness and C coverage, the effect of C is considered to decrease in bulk free energy of Ge in nucleation process, that is, C led to reduce nucleation barrier height and to decrease critical radius.