Electrical and reliability characterization of metal-gate/HfO2/Ge FET’s with Si passivation

Field-effect transistors with metal gate and HfO2 gate dielectric on silicon-passivated germanium substrate are studied. Capacitance-Voltage characteristics show lower gate capacitance at negative gate voltages, irrespective of the device channel polarity. Possible mechanisms for this asymmetry are discussed. Reliability of the metal/high-k gate stack on sub-micron p-channel transistors is evaluated. Time-dependent dielectric breakdown analysis indicates comparable gate-stack quality on germanium and silicon substrates.