Influence of the growth parameters on self-assembled Ge islands on Si(100)

The effect of deposition temperature on the growth dynamic, the shape, the size and the composition of Chemical Vapor Deposition (CVD) grown Ge/Si(100) islands have been investigated in the range between 500 and 850 °C. We found that the growth dynamic of the islands changes strongly between 500 and 600 °C, going from a kinetically limited growth regime to nearly equilibrium conditions. At higher temperatures the island growth is instead mainly affected by Ge/Si alloying. We found that the increase of the growth temperature above 600 °C results in an increased Si/Ge alloying, the mean Ge concentration in the islands changing from x=0.75 at 600 °C to 0.28 at 850 °C. The determined SiGe intermixing and the consequent reduction of the effective mismatch completely accounts for observed island enlargement in the same temperature range.