For heterogeneous integration of III-V compound materials on 200 mm Si wafers, we present a complete in-situ molecular beam epitaxy (MBE) process from a Ge strain compensating buffer on Si to GaAs heteroepitaxy. The whole growth process, including high-k gate oxide deposition, is performed in a 200 mm MBE cluster tool. Thin (<= 0.3 mu m), temperature-graded Ge buffers are investigated and the influence of the substrate temperature during Ge nucleation and anneals is studied. Using such a buffer, GaAs was grown on 200 mm Si wafers and characterized structurally and electrically using MOS capacitors. (C) 2010 Elsevier B.V. All rights reserved.