Mechanisms of carrier generation and transport in Ni-doped Cu2O

The density and mobility of hole carriers in Ni-doped and undoped cuprous oxide (Cu2O) films prepared by pulsed laser deposition (PLD) from Ni-doped and undoped CuO targets, respectively, were measured in order to examine the mechanisms of carrier generation and transport in doped films. The temperature dependence of the carrier density of the films revealed that regardless of the Ni content, the activation energies of the acceptor level of the films are 0.22–0.25 eV. The temperature dependence of the mobility of the films changed from −0.58 to ∼0 by doping with Ni. These results evidenced that hole carriers in Ni-doped Cu2O as well as in undoped Cu2O were generated by Cu vacancies and were primarily scattered by neutral impurity scattering centers. X-ray diffraction (XRD) measurements of the films showed that the mass fraction of Cu2O in the films decreased with increasing Ni content, while that of CuO increased. It was also found that the reduction process of CuO to Cu2O was suppressed by the Ni doping.