Defect engineering of room-temperature ferromagnetism of carbon-doped ZnO

This study investigates the role of carbon (C) in room-temperature (RT) ferromagnetic C : ZnO films. RT ferromagnetism can be observed in air-annealed C: ZnO samples. However, no feature that could be attributed to the incorporation of carbon at O sites (C-O) was observed. An analysis of MCD spectra of the ferromagnetic C: ZnO sample included a non-ferromagnetic peak and a ferromagnetic one. These are related to the loss of carbon and the creation of defects in an air-annealed C : ZnO film by the reaction between C dopants and oxygen. We suggest even if the C dopants are not at C-O sites, C is still a novel dopant to make ZnO ferromagnetic in controlling the defects in the structure formed by suitable post-annealing. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim