Improved electrical properties of HfTiO/GeO x N y gate dielectric Ge MOS capacitors by using wet–NO Ge-surface pretreatment

Reactive cosputtering is employed to prepare high-permittivity HfTiO gate dielectric on n-Ge substrate. Effects of Ge-surface pretreatment on the interface and gate leakage properties of the dielectric are investigated. Excellent performances of Al/HfTiO/GeO x N y /n-Ge MOS capacitor with wet–NO surface pretreatment have been achieved with a interface-state density of 2.1×10 11 eV −1 cm −2 , equivalent oxide charge of −7.67×10 11 cm −2 and gate leakage current density of 4.97×10 −5 A/cm 2 at V g =1 V.