Fabrication and characterization of axially doped silicon nanowire tunnel field-effect transistors

Tunnel field-effect transistors were fabricated from axially doped silicon nanowire p-n junctions grown via the vapor-liquid-solid method. Following dry thermal oxidation to form a gate dielectric shell, the nanowires have a p-n-n⁺ doping profile with an abrupt n-n⁺ junction, which was revealed by scanning capacitance microscopy. The lightly doped n-segment can be inverted to p⁺ by modulating the top gate bias, thus forming an abrupt gated p⁺-n⁺ junction. A band-to-band tunneling current flows through the electrostatically doped p⁺-n⁺ junction when it is reverse biased. Current-voltage measurements performed from 375 down to 4.2 K show two different regimes of tunneling current at high and low temperatures, indicating that there are both direct band-to-band and trap-assisted tunneling paths.