All-(111) surface silicon nanowire field effect transistor devices: Effects of surface preparations

Etching/hydrogen termination of All-(111) surface silicon nanowire field effect (SiNW-FET) devices developed by conventional photolithography and plane dependent wet etchings is studied with X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM) and electrical and electrochemical measurements. All measurements were carried out before and after etching with 1% HF, 40% NH4F, and 40% NH4F (N2) solutions and ozone surface treatments. AFM studies showed higher etching rates for the apex of the triangular nanowires. Stability of as prepared hydrogen terminated SiNW-FET surfaces and their electrical conductivity were considered. Surface etched devices were operated efficiently in an aqueous 0.02 M KCl solution within a small potential window and a reference electrode was found to be essential. Retention of surface positive charges and inversion of p-type to n-type device character have been discussed.