Structural and thermodynamic consideration of metal oxide doped GeO2 for gate stack formation on germanium

A systematic investigation was carried out on the material and electrical properties of metal oxide doped germanium dioxide (M-GeO2) on Ge. We propose two criteria on the selection of desirable M-GeO2 for gate stack formation on Ge. First, metal oxides with larger cation radii show stronger ability in modifying GeO2 network, benefiting the thermal stability and water resistance in M-GeO2/Ge stacks. Second, metal oxides with a positive Gibbs free energy for germanidation are required for good interface properties of M-GeO2/Ge stacks in terms of preventing the Ge-M metallic bond formation. Aggressive equivalent oxide thickness scaling to 0.5 nm is also demonstrated based on these understandings. (C) 2014 AIP Publishing LLC.