Abstract-Passivation of Ge has been a critical issue for Ge MOS applications in future technology nodes. In this letter, we introduce ozone-oxidation to engineer Ge/insulator interface. Interface states (D it ) values across the bandgap and close to conduction bandedge were extracted using conductance technique at low temperatures. D it dependency on growth conditions was studied. Minimum D it of of 3x10 11 cm -2 V -1 was demonstrated. Physical quality of the interface was investigated through Ge 3d spectra measurements. We found that the interface and D it is strongly affected by the distribution of oxidation states and quality of the suboxide.

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We investigate the electrical properties of germanium-channel metal-oxide-semiconductor capacitors with an amorphous atomic-layer-deposited (ALD)-Al2O3 interlayer (IL) and higher-k ALD-TiO2 gate dielectric. An ALD-Al2O3 IL of ∼1 nm thickness reduces the gate leakage current density at the otherwise low band-offset TiO2/Ge interface by six orders of magnitude at flatband. Devices with the thinnest Al2O3 IL exhibited a low capacitance equivalent thickness of 1.2 nm. The hysteresis of the capacitance-voltage curves was <10 mV for TiO2/Al2O3/Ge capacitors with different Al2O3 thicknesses. We obtained a relatively low minimum density of interface states, Dit ∼3×1011 cm−2 eV−1, suggesting the potential of Al2O3 ILs for higher-k/Ge interface passivation.

The electrical properties of metal-oxide-semiconductor (MOS) capacitors composed of atomic-layer-deposited (ALD) hafnium-dioxide (HfO2) dielectrics and plasma-synthesized interface layers were investigated. MOS capacitor with oxynitride interface layer shows negative flatband voltage (Vfb) shift from the ideal value. Hafnium-alkylamide ALD process performed on a plasma nitrided silicon surface causes negative Vfb shift. Germanium MOS capacitors show additional negative Vfb shift (−0.5V). X-ray photoelectron spectroscopy shows evidence of germanium diffusion into the HfO2 layer. Germanium MOS capacitor with tantalum-oxynitride (TaON) interface layer shows superior electrical properties. These results indicate that the selection of the interface layer strongly influences germanium MOS capacitor electrical properties.