Electrical properties of individual tin oxide nanowires contacted to platinum electrodes

Abstract

A simple and useful experimental alternative to field-effect transistors for measuring electrical properties (free electron concentration ${n}_{d}$, electrical mobility $\ensuremath{\mu}$, and conductivity $\ensuremath{\sigma}$) in individual nanowires has been developed. A combined model involving thermionic emission and tunneling through interface states is proposed to describe the electrical conduction through the platinum-nanowire contacts, fabricated by focused ion beam techniques. Current-voltage $(I\text{\ensuremath{-}}V)$ plots of single nanowires measured in both two- and four-probe configurations revealed high contact resistances and rectifying characteristics. The observed electrical behavior was modeled using an equivalent circuit constituted by a resistance placed between two back-to-back Schottky barriers, arising from the metal-semiconductor-metal $(M\text{\ensuremath{-}}S\text{\ensuremath{-}}M)$ junctions. Temperature-dependent $I\text{\ensuremath{-}}V$ measurements revealed effective Schottky barrier heights up to ${\ensuremath{\Phi}}_{BE}=0.4\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$.