High-mobility and low-parasitic resistance characteristics in strained Ge nanowire pMOSFETs with metal source/drain structure formed by doping-free processes

Metal source/drain (S/D) Ge nanowire MOSFETs with a compressive strain as high as 3.8% were fabricated by the 2-step Ge-condensation technique without intentional doping for the S/D. Record high inversion hole mobility (μ eff = 855 cm2/Vs @ N s = 5×1012cm−2) and saturation drain current 731µA/µm at V d =−1V were achieved among Ge nanowire pFETs ever reported. It is found that the extremely low contact resistivity ρ c ∼ 4×10−8O cm2 for the Schottky contact contributes to the high saturation current as well as the high mobility.