Electrical properties of individual tin oxide nanowires contacted to platinum electrodes

A simple and useful experimental alternative to field-effect transistors for measuring electrical properties (free electron concentration n(d), electrical mobility mu, and conductivity 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-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-S-M) junctions. Temperature-dependent I-V measurements revealed effective Schottky barrier heights up to Phi(BE)=0.4 eV.