We report on a novel Ge CMOSFET with ultra-thin (EOT~14 Å) HfO2/TaN gate stack on p-type Si substrate without using graded SiGe buffer layer. High quality tensile-strained Ge channel (279 nm) is grown directly on Si wafer using a novel heteroepitaxial growth technique at temperature 350oC-600oC. Drain currents of 20μA/μm for p-MOS and 10μA/μm for n-MOS at |Vg-VT|=1.2V were achieved for Lg = 5μm with low gate leakage of 10~10A/cm at 1V. Peak hole mobility (measured by split CV) for the epi-Ge channel is 250cm/Vs, which is more than 2× higher than universal hole mobility in Si. Ge layer is grown under ultrahigh vacuum chemical-vapor-deposition (UHVCVD) and is characterized by atomic forces microscopy, Micro-Raman and TEM with root-mean-square surface roughness (0.425nm), etch pit density of ~6×10 cm and tensile-strain of up to ~0.67%. Monolithic integration of tensile-strained Ge CMOSFET on Si wafer is demonstrated, for the first time.