Formation of Ge dots via a C2/Ge/C1/Si structure through solidphase epitaxy by subsequent annealing at 650°C in a molecular beam epitaxy chamber was investigated. The dot density increased with C1 coverage similar to the case of a Ge/C1/Si structure. This suggests that Si-C bonds at a Ge/Si interface are effective to form small and dense Ge dots. The smallest and densest dots were formed for C1 = 0.5 ML and C2 = 0.1 ML with mean diameter and dot density of 28.3 nm and 9.6 × 1010 cm-2, respectively. However, the dot size and density of the C2/Ge/C1/Si structure was 1.3 times larger and 0.6 times lower than those of the Ge/C1/Si structure in the case of C1 = 0.5 ML, respectively. As a result, it was found that C2 atoms on Ge interfere with the effect of reducing dot size in the Ge/C1/Si structures and therefore Ge dots became large.