Conductance quantization of gold nanowires as a ballistic conductor

Electron transport in gold nanowires is studied by transmission electron microscopy (TEM) simultaneously with conductance measurement by using a scanning tunneling tip as an electrode. Conductance evolution while thinning of a gold nanowire shows sequential steps until it breaks after forming a single atomic chain. The step heights coincide the quantum unit, G₀ = 2e²/h = (12.9 kOmega)^-1, except a little deviation due to multiple reflection. Gold nanowires fabricated in the lang110rang orientation can elongate to a several nanometer in length, and show linear current-voltage relation even for the bias voltage of 0.2 V. Gold nanowires, thus, behave as a ballistic conductor, and their conductance is quantized to carry current, 1 muA per single atomic chain at the bias voltage of 13 mV.