Si/Ge Nanowires as High Performance FETs

Semiconductor nanowires are potential alternatives to conventional planar (MOSFETs). Nanowire FETs (NWFETs) have a unique electronic structure which we can try and exploit. Carriers in nanowires have longer mean free paths and are subjected to reduced scattering thanks to onedimensional quantum confinement effects. Unlike carbon-nanotubes (CNTs), the electronic properties of nanowires are highly reproducible in a large-enough yield required for VLSI systems and applications. In ref. [1], a nanowire based FET using high-k dielectrics in a top-gate geometry was reported (Fig. 1a,b,c). This FET displayed enhanced gate coupling, and a scaled transconductance (∂I/∂V ) and “on” current that was three to four times greater than state-of-the-art MOSFETs. Furthermore, the intrinsic switching delay τ substantially exceeded values obtained in planar silicon MOSFETs.