In this work, we investigate the directly bonded germanium-silicon interfaces to facilitate the development of high quality germanium silicon hetero integration at the wafer scale. X-ray photoelectron spectroscopy data is presented which provides the chemical composition of the germanium surfaces as a function of the hydrophilic bonding reaction at the interface. The bonding process induced long range deformation is detected by synchrotron x-ray topography. The hetero-interface is characterized by measuring forward and reverse current, and by high resolution transmission electron microscopy. © 2011 American Institute of Physics.