Dual-gate operation and carrier transport in SiGe p–n junction nanowires

Abstract

We investigate carrier transport in silicon–germanium nanowires with an axial p–n junction doping profile by fabricating these wires into transistors that feature separate top gates over each doping segment. By independently biasing each gate, carrier concentrations in the n- and p-side of the wire can be modulated. For these devices, which were fabricated with nickel source–drain electrical contacts, holes are the dominant charge carrier, with more favorable hole injection occurring on the p-side contact. Channel current exhibits greater sensitivity to the n-side gate, and in the reverse biased source–drain configuration, current is limited by the nickel/n-side Schottky contact.