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In this paper, we demonstrate high-mobility bulk Ge N- and P-FETs with GeON gate dielectric. The highest electron mobility to date in Ge is reported, and two times improvement over universal hole mobility is achieved for Ge P-FETs. For the first time, the effect of surface orientation on Ge mobility is investigated experimentally. A 50% improvement in electron mobility is shown for the (111) substrate orientation compared to the (100) orientation. Carrier scattering mechanisms are studied through low-temperature mobility measurements and interface characterization. The conductance technique is applied at low temperatures for complete mapping of the density of interface traps (Dit) across the Ge bandgap and also close to the band edges. Carrier scattering mechanisms and the distribution of Dit are compared for Ge NMOS and PMOS.