Reconsideration of electron mobility in Ge n-MOSFETs from Ge substrate side — Atomically flat surface formation, layer-by-layer oxidation, and dissolved oxygen extraction

We clarified wafer-related origins for electron mobility degradation in Ge n-MOSFETs. High-N_s electron mobility was dramatically improved thanks to (i) atomically flat Ge surface formation, followed by (ii) layer-by-layer oxidation. (iii) Oxygen-related neutral impurities in Ge substrates could be another origin of the mobility reduction on Ge wafers. By successfully eliminating these scattering sources in Ge n-MOSFETs, we demonstrated intrinsically high electron mobility in a wide range of N_s.