Comparison of electrical characteristics of back- and top-gate Si nanowire field-effect transistors

Back- and top-gate field-effect transistors (FETs) with channels composed of p-type Si nanowires were fabricated by a conventional photolithographic process and their electrical properties were characterized by conventional current–voltage (I–V)(I–V) measurements. For a representative top-gate FET, the peak transconductance was enhanced from 2.24 to 72.2 nS, the field-effect mobility from 1.7 to 3.1 cm2/V s, and the Ion/Ioff ratio from 2.21 to 2.49×106, compared with those of a representative back-gate FET. The observed improvement of the electrical characteristics is mostly attributed to both the top-gate geometry and the relatively thin gate layer.