Conductance quantization in nanoscale vertical structure silicon field-effect transistors with a wrap gate

Experimental results of quantum ballistic transport in single quantum contact by using vertical structure silicon field effect transistors with a wrap gate are presented. Based on dc measurement, the conductance–voltage characteristics show quantized plateaus at multiples of $2e2/h.$ The devices were prepared by electron beam lithography and by combinations of various types of etching. The channel is fabricated by the chemical vapor deposition of amorphous silicon and solid-phase crystallization. The vertical structure allows a channel length as short as 30 nm, which is defined by the film thickness. The effective channel is reduced by the depletion potential, resulting in a much narrower channel width compared to the geometrical width of 60 nm. Thus, the effective size of the silicon transistor is smaller than the elastic mean free path of 40 nm, resulting in the conduction quantization at $3–5 K.$