Formation of a stepped Si(100) surface and its effect on the growth of Ge islands

The transition from a two-domain to one-domain surface on a Si(100) substrate is investigated. It is demonstrated using reflection high-energy electron diffraction that at a temperature of 600$^{\circ}$C and a deposition rate of 0.652 $\mathring{\mathrm{A}}$/s onto a Si(100) substrate pre-heated to 1000$^{\circ}$C and inclined at an angle of 0.35$^{\circ}$C to the plane, a series of reflections from the 1 $\times$ 2 superstructure completely vanishes at a constant flow of Si. This is attributed to the transition of the surface from monoatomic to diatomic steps. At growth rates lower than 0.652 $\mathring{\mathrm{A}}$/s, the transition from a two-domain to one-domain surface is also observed; with a decrease in the growth rate, the intensity ratio $I_{2\times1}/I_{1\times2}$ decreases and the maximum of the dependences shifts toward lower temperatures. The complete vanishing of the series of superstructural reflections after preliminary annealing at a temperature of 700$^{\circ}$C is not observed; this series only vanishes after annealing at 900 and 1000$^{\circ}$C. The growth of Ge islands on a Si(100) surface preliminary annealed at a temperature of 800$^{\circ}$C is studied. It is shown that the islands tend to nucleate at the step edges. A mechanism of Ge island ordering on the Si(100) surface is proposed.