We report on systematic measurements of the dephasing of the free excitonic transition in individual ZnO nanowires with a diameter of about 70 nm. The temperature-dependent intensity of the free exciton ͑FX͒ emission is well reproduced by a thermally activated behavior having two constant activation energies of 5.98 and 30.63 meV. The FX linewidth broadening with temperature reveals the dephasing of FX scattered by acoustic phonons rather than longitudinal optical phonons. These findings indicate that the dephasing mechanism scattering from acoustic phonons in individual ZnO nanowires result from the compensation of acoustic phonons to the nonconservation of crystal momentum.

We have fabricated a novel device composed of a single ZnO wire bridged on a pair of Au electrodes. The charge transport in Au/single ZnO wire/Au is investigated by the current-voltage measurement. A negative differential resistance behavior (NDR) in current-voltage curve of single compound semiconductor wire is first observed at room temperature. A peak-to-valley current ratio is greater than 3:1. The NDR may be due to a specific metal-wire surface contact nanoscale contacts and electronic coupling between a single ZnO wire and Au electrodes. It is expected that ZnO wire can be applied to the nanoelectronic devices.