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 cm
²
/Vs @ N
_s
= 5×10
¹²
cm
^-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
^-8
O cm
²
for the Schottky contact contributes to the high saturation current as well as the high mobility.