Ultra-Thin, High Quality HfO2 on Strained-Ge MOS Capacitors with Low Leakage Current

Ultra-thin HfO2 MOS capacitors on strained-Ge (s-Ge) have been fabricated with an extracted effective oxide thickness (EOT) of 4.9 Å and leakage current less than 0.2 A/cm at |VG| < 0.5 V. The CV measurements show little hysteresis and areal capacitance scaling for 50×50 to 200×200 μm devices. A high series resistance is observed, likely due to a 500 meV valence band offset between the s-Ge and relaxed, p-type Si0.55Ge0.45 virtual substrate. The capacitance results suggest an extremely-scaled, high quality dielectric on s-Ge promising for deeply scaled CMOS.