Monolithic integration of tensile-strained Si/Germanium (Ge)-channel n-MOS and tensile-strained Ge p-MOS with ultrathin (equivalent oxide thickness similar to 14 angstrom) HfO2 gate dielectric and TaN gate stack on Si substrate is demonstrated. Defect-free Ge layer (279 nm) grown by ultrahigh vacuum chemical-vapor deposition is achieved using a two-step Ge-growth technique coupled with compliant Si/SiGe buffer layers. The epi-Ge layer experiences tensile strain of up to similar to 0.67% and exhibits a peak hole mobility of 250 cm(2)/V. S which is 100% higher than the universal Si hole mobility. The gate leakage current is two orders of magnitude lower compared to the reported results on Ge bulk.