Improved Electrical Characteristics of Ge MOS Devices With High Oxidation State in ${\rm HfGeO}_{\rm x}$ Interfacial Layer Formed by In Situ Desorption

Ge MOS devices with about 95% Ge
⁴⁺
in HfGeO
_x
interfacial layer are obtained by H
₂
O plasma process together with in situ desorption before atomic layer deposition (ALD). The equivalent oxide thickness is scaled down to 0.39 nm; the leakage current is decreased as well. The improvement can be attributed to the in situ Ge suboxide desorption process in an ALD chamber at 370 °C. The interface trap density and frequency dispersion need further process development to be reduced.