Ge MOSFETs have generated a strong interest as a current drive enhancement technology beyond strained-Si technologies. The key technologies for realizing Ge MOSFETs are the formation of superior MOS interfaces. However, control technologies of to provide superior Ge MOS/MIS interfaces has not been fully established yet. In this report we review recent technologies for controlling Ge MOS interfaces. In particular, we report the interface properties of thermally-oxidized GeO2/Ge and Si-passivated GeO2 interfaces in detail. In addition, we introduce a new measurement method for studying the physical origin of low current drive in Ge n-MOSFETs, where electron and hole mobility of SiO2/Ge interfaces are evaluated for an identical MOS interface by using metal source/drain GOI MOSFETs with a Kelvin pattern.