| Summary: | 碩士 === 國立交通大學 === 應用化學系分子科學碩博士班 === 102 === This study examined carrier transport in single cobalt-doped ZnO nanorod under magnetic field of -5 Tesla to 7 Tesla at low temperature. Measurements were taken on single nanorods deposited on a Si template, where two point metallic contacts were previously made using e-beam lithography, dielectrophoresis, and focused ion beam. In two probe measurements, the current-voltage curves were clearly linear and symmetrical with respect to both axes in temperatures ranging from 1.4 K to 300 K. The Co-doped nanorods exhibited ferromagnetic behavior from room temperature to 5 K and the remanence permanent magnet of the nanorods increased with increasing Co concentrations. When applied magnetic field, the electrical resistance of Co-doped ZnO increases about 1%. We attribute the increase of resistance in the Co-doped ZnO nanorod to the splitting of conduction band and the re-distribution of electrons under magnetic field. On the contrary, the magnetoresistance of pure ZnO nanorods was decreased because of the breakdown of the weak localization under magnetic field.
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