Ge-Interface Engineering With Ozone Oxidation for Low Interface-State Density

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. Density of interface states (D_it) across the bandgap and close to the conduction band edge was extracted using conductance technique at low temperatures. D_it dependence on growth conditions was studied. Minimum D_it of 3 times 10¹¹ cm^-2V^-1 was demonstrated. Physical quality of the interface was investigated through Ge 3d spectra measurements. We found that the interface and D_it are strongly affected by the distribution of oxidation states and the quality of the suboxide.