It has been found that Ni forms ohmic contacts and Ti forms Schottky-barrier contacts to boron nanowires. Using two-step electron beam lithography, Ni and Ti electrodes are subsequently attached onto the ends of a single boron nanowire. As a result, a nanoscale rectifier is created using a boron nanowire.

Single-crystal ZnO nanowires are synthesized using a vapor trapping chemical vapor deposition method and configured as field-effect transistors. Electrical transport studies show n-type semiconducting behavior with a carrier concentration of similar to10(7) cm(-1) and an electron mobility of similar to17 cm(2)/V s. The contact Schottky barrier between the Au/Ni electrode and nanowire is determined from the temperature dependence of the conductance. Thermionic emission is found to dominate the transport mechanism. The effect of oxygen adsorption on electron transport through the nanowires is investigated. The sensitivity to oxygen is demonstrated to be higher with smaller radii nanowires. Moreover, the oxygen detection sensitivity can be modulated by the gate voltage. These results indicate that ZnO holds high potential for nanoscale sensing applications. (C) 2004 American Institute of Physics.