The present paper summarizes results of thermal annealing steps on epitaxially grown Si buffer morphology in dependence of Si offcut angle as well as miscut direction. A Si buffer layer was grown on an undulated Si substrate by vapour phase epitaxy, which provides due to its roughness deliberate off-orientations. An optimized annealing procedure under a hydrogen pressure of 950 mbar was used after growth. Atomic force investigation shows that there is a clear tendency to form bi-atomic steps along both < 110 > directions as long as the surface miscut is low in angle. For the off-orientations in between these two directions the surface steps delimit mono-layer high terraces. An exact (001) Si substrate with a low miscut of 0.12 degrees towards [1 (1) over bar0] was treated by the same annealing condition. The Si surface is strongly dominated by one kind of sublattice but not completely double-stepped. Using this Si wafer as a substrate for GaP heteroepitaxy by metal organic vapour phase epitaxy, an antiphase domain free GaP layer is achieved after 50 nm of overgrowth, proven by transmission electron microscopy investigation. (C) 2008 Elsevier B.V. All rights reserved.