The authors present results on fabricating ultra-thin silicon nanowires on insulators and characterizing their electrical conductivity. The silicon nanowires were fabricated by atomic force microscopy lithography on ultra-thin (8 nm) silicon on insulator substrates. At such minute thicknesses, the device exhibits high sensitivity to the charges trapped at the Si/SiO2 interface. This leads to an unusual behavior of the electrical conductivity of the nanowires as a function of drain-source and gate voltages. (c) 2008 American Vacuum Society.