Electrical properties and near band edge emission of Bi-doped ZnO nanowires

Electrical transport of Bi-ZnO nanowires shows n -type semiconducting behavior with a carrier concentration of ∼3.5× 108 cm-1 (2.7× 1019 cm-3) and an electron mobility of 1.5 cm2 V s. The carrier concentration is one order of magnitude larger than that of undoped ZnO nanowires, indicating that Bi acts as donor rather than the usual acceptor in ZnO films. The low mobility may be in association with electron scatterings at the boundaries from small size effect of nanowires. Near band edge emission in photoluminescence spectrum of Bi-ZnO nanowires is redshifted relative to undoped ZnO nanorods as a result of enhanced carrier concentration. The donor-acceptor pair transition associated with Bi was also observed at 3.241 eV.