Synthesis, fabrication, and characterization of Ge/Si axial nanowire heterostructure tunnel FETs

Axial Ge/Si heterostructure nanowires allow energy band-edge engineering along the axis of the nanowire, which is the charge transport direction, and allows the realization of novel asymmetric device architectures. This work reports on two advances in the area of heterostructure nanowires and tunnel FETs: (i) the realization of 100 % compositionally modulated Si/Ge axial heterostructure nanowires with lengths suitable for device fabrication and (ii) the design and implementation of Schottky barrier tunnel FETs on these nanowires for high-on currents and suppressed ambipolar behavior. Initial prototype devices resulted in a current drive in excess of 100 μA/μm (I/πD) and 10⁵ I_on/I_off ratios. These results demonstrate the potential of such asymmetric heterostructures (both in the semiconductor channel and at the metal-semiconductor interfaces) for low-power and high performance electronics.