Axial bandgap engineering in germanium-silicon heterostructured nanowires

Large composition changes along the nanowire axial direction provide an additional degree of freedom for tailoring charge transport in semiconductor devices. We utilize 100% axial composition modulated germanium to silicon semiconductor nanowires to demonstrate bandgap-engineered Schottky barrier heterostructured field-effect transistors that outperform their homogenous counterparts. The built-in electric field in the channel provided by the compositional change and asymmetric Schottky barrier heights enables high carrier injection in one transport direction but not the other, resulting in high on-currents of 50 mu A/mu m, 10(7) I-on/I-off ratios, and no ambipolarity in transfer characteristics. (C) 2011 American Institute of Physics. [doi:10.1063/1.3634050]