Junctionless Gate-All-Around pFETs Using <italic>In-situ</italic> Boron-Doped Ge Channel on Si

Abstract

Junctionless devices exhibit favorable $I_{{\rm on}}/I_{{\rm off}}$ and SS in high-mobility Ge channels owing to the elimination of junction leakage. With channel doping of 5 × 1018 cm−3, the fin width of 27 nm and the gate length of 250 nm, our gate-all-around device has the $I_{{\rm on}}/I_{{\rm off}}$ of 1 × 106, the SS of 95 mV/dec, and the $I_{{\rm on}}$ of 275 μA/μm. The drain current reaches 390 μA/μm for the device with channel doping of 8 × 1019 cm−3, and the fin width of 9 nm. The junctionless devices show higher mobility in the large $V_{{\rm GS}} -V_{T}$ region than the inversion mode devices due to less dependence on surface roughness scattering. Junctionless devices also show increasing drive current at increasing temperatures due to the nature of impurity scattering.