High performance Ge junctionless gate-all-around NFETs with simultaneous Ion =1235 μA/μm at Vov=Vds=1V, SS=95 mV/dec, high Ion/Ioff=2×106, and reduced noise power density using S/D dopant recovery by selective laser annealing

Abstract

The low channel doping concentrations of 1.2×10¹⁹ cm⁻³ to deplete the channel and the high S/D doping of 1.2×10²⁰ cm⁻³ to reduce the S/D resistance are achieved simultaneously by selective laser annealing on the same CVD P-doped epi-Ge on SOI without ion implantation. The device with Wfin down to 7 nm, EOT = 2.2 nm, and Lch = 60 nm has Ion = 1146 μA/pm, Ion/Ioff = 2×10⁶, and SS = 95 mV/dec. The Ion can be further boost to 1235 μA/μm with external uniaxial tensile strain of 0.16%. The self-heating effect is responsible in part for such high Ion, because the high device temperature can reduce the dominant impurity scattering in the channel. The increasing mobility with increasing temperature indicates the impurity scattering is dominant. The lower low frequency noise is observed with junctionless (JL) gate-all-around (GAA) FETs than planar inversion mode (INV) devices due to the bulk conduction nature of JL FETs.