Ultrathin (<10 nm) zirconium oxide (ZrO 2 ) films have been deposited at low temperature (150 °C) on strained-Si on relaxed-Si 0.8 Ge 0.2 substrates by microwave plasma enhanced chemical vapor deposition (PECVD). Interfacial and electrical properties of Al/ZrO 2 /strained-Si MOS capacitors have been characterized using capacitance–voltage (C–V) and conductance–voltage (G–V) techniques. It is observed that D it ranges from 4.93×10 12 eV − 1 cm − 2 in (E C −0.35) eV to 1.86×10 12 eV − 1 cm − 2 in (E C −0.82) eV and decays slowly while the time constant (τ) ranges from 3.05×10 − 6 s in (E C −0.38) eV to 1.24×10 − 5 s in (E C −0.83) eV and rises slowly as the interface state energy is changed from the bottom of the conduction band (E C ) towards the mid-gap. Extracted value of electron capture cross-section, σ n ranges from ~2×10 − 12 to ∼9×10 − 13 cm 2 and doping concentration, N d shows a value of ∼4.97×10 16 cm − 3 .